Glossary of Terms¶

Abstraction¶

The practice of hiding unnecessary detail behind a simpler interface so a system can be used or understood without knowing exactly how it works internally.

Example: Calling pixels.fill("red") on a NeoPixel strip lets a student set every LED's color without writing the low-level timing code that actually sends data to each chip.

See also: Neopixel Library

Access Point Mode¶

A wireless configuration in which a device creates its own Wi-Fi network for other devices to join, rather than joining an existing network.

Example: A Pico W in access point mode lets a phone connect directly to it to configure settings before it has joined a home Wi-Fi network.

Contrast with: Station Mode

Accessibility Lighting Cue¶

A lighting pattern specifically designed to communicate information visually to users who may not be able to rely on sound-based feedback.

Example: A Pi 500+ keyboard project flashes the Caps Lock key red instead of playing a chime when a new chat message arrives, so a hard-of-hearing student still gets the alert.

See also: Visual Feedback Design

Active Buzzer¶

A piezo buzzer with a built-in oscillator that produces a single fixed tone whenever powered on, requiring no frequency control from the microcontroller.

Example: An active buzzer wired to a GPIO pin makes the same beep every time the pin is set high, regardless of how long it stays on.

Contrast with: Passive Buzzer

Active Cooling¶

A cooling method that uses a fan to actively move air across a component to remove heat, rather than relying on passive heat dissipation alone.

Example: The Raspberry Pi 5's official Active Cooler uses a small fan mounted over a heat sink to keep the Broadcom BCM2712 running cool during a long object-detection session with the AI HAT+.

Contrast with: Heat Sink

See also: Thermal Throttling

Actuator¶

A component that converts an electrical signal from a microcontroller into physical motion, light, sound, or another real-world effect.

Example: A DC motor is an actuator that turns electrical current into the spinning motion that drives a robot's wheels.

See also: Output Device, Sensor

Addressable LED¶

An LED that contains its own small controller chip, allowing software to set its individual color and brightness independently of every other LED on the same strip.

Example: In an addressable LED strip, pixel 5 can glow blue while pixel 6 stays off, all controlled from a single data pin.

Contrast with: LED, which has no built-in controller and can only be switched fully on or off as a group.

See also: NeoPixel, WS2812B LED

AI HAT Plus¶

An official add-on board for the Raspberry Pi 5 that adds a dedicated neural processing unit, enabling fast, real-time machine learning inference for tasks like image and sound recognition.

Example: With the AI HAT+ attached, a Raspberry Pi 5 can recognize objects in a camera feed at a much higher frame rate than the main processor could achieve alone.

See also: Neural Processing Unit, Hailo Accelerator

Alarm Feature¶

A clock or watch capability that triggers a sound, light, or notification at a specific, previously set time.

Example: A DS3231-based wristwatch project lets a student set a 7:00 AM alarm that flashes the round display and sounds a piezo buzzer until a button is pressed to dismiss it.

See also: Timer Feature

Alert Sound Trigger¶

A programmed response that activates a specific action, such as flashing a NeoPixel, when a particular environmental sound class is detected.

Example: In the audio-classification chapter, a Pi 5 program flashes a connected NeoPixel red whenever its sound model detects a smoke-alarm class with high confidence.

See also: Environmental Sound Class

Algorithm¶

A finite, ordered sequence of precise steps that transforms given inputs into a desired output or result.

Example: A simple algorithm for blinking an LED is: turn the pin on, wait, turn the pin off, wait, and repeat.

See also: Pseudocode, Flowchart

Algorithm Design¶

The process of planning the ordered set of steps a program will follow to solve a problem, including choices about how data is checked, transformed, and acted on.

Example: Designing the algorithm for a line-following robot means deciding, in order, when to read the sensors, how to compare readings, and which motor commands to send.

Ambient Lighting Mode¶

A keyboard lighting style that displays a slow, continuous background pattern unrelated to specific key presses, intended to set a mood rather than provide feedback.

Example: A Pi 500+ desk setup slowly cycles the keyboard backlight through blues and purples over several minutes, unrelated to any key presses, just to set a calm mood while studying.

Contrast with: Reactive Lighting

Amplifier Module¶

A circuit that boosts the strength of an audio signal so it is powerful enough to drive a speaker at an audible volume.

Example: A small audio amplifier board sits between a Pico's PWM audio output and a speaker so a chapter-18 sound-classification project can play an audible alert tone.

See also: Speaker Output

Analog Audio Signal¶

A continuously varying electrical signal that directly represents a sound wave's changing amplitude over time, before it is converted into digital form.

Example: A USB microphone plugged into a Pi 5 first captures the room's sound as a continuously varying analog audio signal before the sound card converts it into digital samples for a classification model.

Contrast with: Digital Audio Signal

Analog Clock Hands¶

Graphical lines drawn on a display, pivoting from a center point, that indicate hours, minutes, and sometimes seconds in the style of a traditional mechanical clock face.

Example: A program recalculates the angle of the analog clock hands every second and redraws them on a round display.

Contrast with: Digital Clock Format

Analog Pin¶

A GPIO pin capable of reading a continuously varying voltage level, rather than just an on or off state, typically through an analog-to-digital converter.

Example: An analog pin reads the changing voltage from a photoresistor's voltage divider as light levels shift.

Contrast with: Digital Pin

See also: Analog To Digital Converter

Analog Read¶

An operation that measures the current voltage present on an analog pin and returns it as a numeric value a program can use.

Example: An analog read of a potentiometer's wiper pin returns a number that changes smoothly as the knob is turned.

Contrast with: Digital Read

See also: Analog To Digital Converter

Analog To Digital Converter¶

A circuit, often built into a microcontroller, that measures a continuously varying voltage and converts it into a numeric value a program can use.

Example: The analog-to-digital converter inside a Raspberry Pi Pico turns a photoresistor's changing voltage into a number between 0 and 65535.

See also: Analog Pin, Analog Read

Animation Frame¶

A single, complete image or lighting state displayed for a brief moment as part of a sequence that creates the illusion of motion or change over time.

Example: Each animation frame of a chase animation shows the lit pixel shifted one position further along the strip than the previous frame.

See also: Frame Rate

Animation Timing¶

The scheduling of when each frame of an animation should be drawn, controlling both the speed and smoothness of the resulting motion.

Example: A NeoPixel chase animation uses a fixed delay of 50 milliseconds between frames so the moving light appears smooth rather than jumpy on the LED strip.

See also: Frame Rate, Non Blocking Code

APT Package Manager¶

The specific package manager used by Raspberry Pi OS and other Debian-based Linux systems to install and update software from online repositories.

Example: A student types sudo apt install python3-picamera2 in the terminal to install the camera library needed for the Pi 5 object-detection project.

See also: Package Manager, Install Package Command

Assessment Rubric¶

A scoring guide that describes specific criteria and performance levels used to evaluate student work consistently and fairly.

Example: A teacher grading the capstone project uses a rubric that awards points separately for working code, a clear design brief, and a five-minute demo presentation.

See also: Student Portfolio

Audio Buffer¶

A temporary block of memory used to hold a short chunk of digital audio samples while they are being processed or transmitted.

Example: A Pi 5 sound-classification script fills a one-second audio buffer from the USB microphone before running it through the model, rather than analyzing samples one at a time.

See also: Digital Audio Signal

Audio Confidence Score¶

A confidence score specifically produced by a sound or speech recognition model, indicating how certain it is about a classification or transcription.

Example: A wake-word program only triggers the robot's response when its audio confidence score for the phrase "hey robot" exceeds 0.85, avoiding false alarms from similar-sounding words.

See also: Confidence Score, Sound Classification

Audio Feature Extraction¶

The process of converting a raw digital audio signal into a smaller set of meaningful numeric values that better capture the characteristics a sound-recognition model needs.

Example: Before classifying a recorded bark or doorbell sound, the chapter-18 pipeline performs audio feature extraction, converting the raw waveform into a Mel-frequency cepstrum the model can interpret.

See also: Mel Frequency Cepstrum, Audio Preprocessing Pipeline

Audio Latency¶

The delay between a sound occurring and a device finishing processing or responding to it.

Example: A voice-command robot needs low audio latency so it starts turning within a fraction of a second of hearing "turn left," rather than pausing noticeably before responding.

See also: Inference Latency

Audio Model Inference¶

The process of running a captured audio clip through a trained sound or speech recognition model to produce a classification or transcription.

Example: After capturing a two-second clip from the USB microphone, the Pi 5 program runs audio model inference to decide whether the clip contains a dog bark or background noise.

See also: Model Inference, Sound Classification

Audio Preprocessing Pipeline¶

The sequence of steps, such as filtering and feature extraction, applied to raw audio before it is fed into a sound-recognition model.

Example: The chapter-18 project's audio preprocessing pipeline filters out low-frequency hum, normalizes volume, and extracts frequency features before any clip reaches the sound classifier.

See also: Audio Feature Extraction, Camera To Model Pipeline

Audio Privacy Considerations¶

The ethical and practical concerns around recording, storing, or transmitting audio that may capture identifiable voices or private conversations.

Example: A classroom discussion before building the microphone-based robot addresses audio privacy considerations, reminding students not to record classmates without telling them first.

See also: On Device Processing

Audio Sampling Rate¶

The number of times per second an analog sound wave is measured and converted into digital values, which determines the highest frequency the recording can accurately capture.

Example: A common audio sampling rate of 16,000 samples per second is often sufficient for speech and keyword recognition.

See also: Sampling Rate, Digital Audio Signal

Autofocus Camera¶

A camera module capable of automatically adjusting its lens position to keep a subject sharp, without requiring a manual focus adjustment. A fixed-focus module, by contrast, has no such mechanism and stays sharp only within a preset distance range.

Example: The Raspberry Pi Camera Module 3 is an autofocus camera, automatically sharpening a close-up shot of a hand for a chapter-17 object-detection demo without the student adjusting anything.

A robot's ability to move through an environment and make movement decisions on its own, using sensor data, without a human directly controlling each action.

Example: During autonomous navigation, a robot decides on its own when to turn based only on its ultrasonic sensor readings.

Bash Shell¶

A widely used shell program on Linux systems, including Raspberry Pi OS, that interprets typed commands and runs shell scripts.

Example: A student opens a terminal on the Pi 500+ and types Linux commands at the Bash shell to navigate folders and run their Python scripts.

See also: Shell, Shell Script

Battery Life Optimization¶

The set of techniques used to reduce a portable device's power consumption so its battery lasts as long as possible between charges.

Example: A wearable watch project uses deep sleep between display refreshes as part of battery life optimization, letting a coin-cell-powered wristwatch run for weeks instead of days.

See also: Sleep Mode, Deep Sleep, Low Power Design

Battery Pack¶

An enclosure holding one or more batteries connected together to supply power to a portable device or robot.

Example: A STEM robot kit's chassis holds a four-AA battery pack that supplies power to both motors and the Pico controlling them.

See also: Rechargeable Battery, Power Switch

Battery Safety¶

Practices that reduce the risk of fire, chemical leakage, or injury when storing, charging, or using batteries in a project.

Example: The robot-building chapter's safety guidelines remind students to never puncture or short-circuit the lithium battery pack used in some robot kits, following basic battery safety practices.

See also: Rechargeable Battery, Safety Guidelines

Behavior Tree¶

A hierarchical structure used to organize a robot's decision-making, in which higher branches represent more general behaviors and lower branches represent specific actions, evaluated in order of priority.

Example: A STEM robot's behavior tree checks "is an obstacle detected?" first; if not, it falls through to a lower branch that simply drives forward, keeping the decision logic organized by priority.

See also: Priority Based Behavior, State Machine

Bill Of Materials¶

An itemized list of every part, component, and quantity needed to build a project, often including estimated cost and supplier for each item.

Example: A bill of materials for the NeoPixel wearable project lists one Pico, one strip of eight NeoPixels, a coin cell holder, and wire.

See also: Component Sourcing

BLE Advertising¶

The process by which a Bluetooth Low Energy device periodically broadcasts small packets of information announcing its presence so nearby devices can discover it.

Example: A Pico W wearable sensor project continuously performs BLE advertising, broadcasting a small packet every second so a nearby phone app can discover and connect to it.

See also: Bluetooth Low Energy, BLE Peripheral

BLE Central¶

A Bluetooth Low Energy device, typically a phone or computer, that scans for and connects to nearby peripheral devices in order to use their services.

Example: A smartphone running a Bluetooth scanner app acts as the BLE central, searching for and connecting to a student's Pico W-based wearable that is broadcasting sensor data.

Contrast with: BLE Peripheral

BLE Characteristic¶

A single piece of readable or writable data offered by a Bluetooth Low Energy service, such as a specific sensor's current value.

Example: A wearable's heart rate BLE characteristic can be read by a connected phone app to display the current value.

See also: BLE Service

BLE Peripheral¶

A Bluetooth Low Energy device, such as a wearable sensor, that advertises its presence and offers services for a central device to connect to and use.

Example: In the wireless-communication chapter, a Pico W wearable heart-rate demo runs as a BLE peripheral, offering its sensor readings for a phone to connect to and read.

Contrast with: BLE Central

See also: BLE Advertising, BLE Service

BLE Service¶

A grouped collection of related data and functions that a Bluetooth Low Energy peripheral offers, made up of one or more individual characteristics.

Example: A Pico W wearable project defines a single BLE service containing a temperature characteristic and a battery-level characteristic that a connected phone app can read.

See also: BLE Characteristic, BLE Peripheral

Blink An LED¶

A traditional first physical computing exercise in which a program repeatedly turns a GPIO pin on and off to make an LED flash, confirming that the hardware and code both work.

Example: The blink an LED project is often the very first program a student runs on a new Raspberry Pi Pico.

Blink Animation¶

A short animation that briefly closes and reopens a robot's drawn eyes, used to make its expression feel more lifelike.

Example: An OLED-equipped robot's face briefly closes both drawn eyes for two frames every few seconds, a blink animation that keeps its expression from looking frozen.

See also: Eye Shape, Idle Animation

Bluetooth Low Energy¶

A short-range wireless communication standard designed to transfer small amounts of data using very little power, well suited to battery-powered wearables and sensors.

Example: A Pico W-based wearable watch uses Bluetooth Low Energy to send step-count data to a phone app without draining its coin-cell battery in a single afternoon.

See also: BLE Advertising, BLE Peripheral

Boot Process¶

The sequence of steps a computer follows from being powered on until its operating system is fully loaded and ready for use.

Example: When a student powers on a Raspberry Pi 500+, the boot process loads Raspberry Pi OS from the microSD card and ends with the desktop appearing on screen.

See also: SD Card Imaging

Bounding Box¶

A rectangle drawn around a detected object in an image, marking its approximate location and size.

Example: The Pi 5 object-detection demo draws a green bounding box around each detected face in the camera's live video feed.

See also: Object Detection

Breadboard¶

A reusable prototyping board with a grid of small spring clips that let components and wires be connected without soldering, commonly used to build and test circuits temporarily.

Example: Students push an LED, a resistor, and jumper wires into a breadboard to build their first circuit.

See also: Breadboard Rail, Breadboard Row

Breadboard Rail¶

A long strip of connected holes running along the top or bottom edge of a breadboard, typically used to distribute power or ground to multiple parts of a circuit.

Example: The red-marked positive rail on a breadboard carries 3.3 volts to every component that needs power.

See also: Breadboard, Power Rail

Breadboard Row¶

A short strip of five connected holes in the central area of a breadboard, used to electrically join components that are plugged into the same row.

Example: Placing a resistor's leg and an LED's leg in the same breadboard row connects them electrically without any wire.

See also: Breadboard

Brightness¶

The attribute of a color describing how light or dark it appears, independent of its hue or saturation, often controlled separately to dim or brighten a display.

Example: Reducing brightness on a NeoPixel strip at night keeps the same colors but makes them less intense.

See also: Hue, Saturation, Brightness Scaling

Brightness Scaling¶

The process of adjusting a whole strip's overall light output by multiplying every pixel's color values by a common factor, without changing the underlying colors.

Example: Brightness scaling a strip to 20 percent keeps the same rainbow pattern but makes it much dimmer for nighttime use.

See also: Brightness

Broadcom BCM2712¶

The system-on-chip that serves as the main processor in the Raspberry Pi 5, providing the CPU, GPU, and memory controller for that board.

Example: The Broadcom BCM2712 chip inside the Raspberry Pi 5 is powerful enough to run a real-time object-detection pipeline when paired with the AI HAT+.

See also: Raspberry Pi 5, System On Chip

Bulk Discount¶

A reduced per-unit price offered by a supplier when components are purchased in large quantities.

Example: A teacher ordering 30 STEM robot kits for a classroom set qualifies for a bulk discount that lowers the per-kit price compared to buying a single kit.

See also: Bulk Purchasing

Bulk Purchasing¶

Buying components or kits in large quantities, often at a reduced per-unit price, to equip an entire classroom or program at once.

Example: A school district uses bulk purchasing to order NeoPixel strips, breadboards, and Pico boards for an entire grade level at once rather than one classroom at a time.

See also: Bulk Discount, Classroom Budget

Button Debounce Code¶

Software logic that ignores rapid, spurious signal changes from a mechanical button so that a single physical press is registered as exactly one event.

Example: Button debounce code waits 50 milliseconds after detecting a press before checking the pin again, filtering out the switch's initial electrical chatter.

See also: Debounce, Push Button

Buzzer Melody¶

A short sequence of musical notes played on a passive buzzer, often used to signal a specific event, such as startup or task completion.

Example: A STEM robot plays a short rising buzzer melody on its passive buzzer when it completes a maze-navigation task successfully.

See also: Tone Generation, Sound Feedback

Calibration¶

The process of adjusting a sensor's readings or a program's threshold values to match real-world conditions, often by taking test measurements in the actual environment where the device will be used.

Example: Calibration of a photoresistor circuit involves recording its reading in a dark room and a bright room, then setting a threshold value between the two.

See also: Threshold Value, Robot Calibration

Camera Module¶

An official add-on board containing an image sensor that connects to a Raspberry Pi's Camera Serial Interface to capture photos and video.

Example: The Raspberry Pi Camera Module 3 connects to a Pi 5's Camera Serial Interface and supplies the live video feed used in the chapter-17 object-detection project.

See also: Camera Serial Interface, Image Sensor

Camera Resolution¶

The number of individual pixels a camera module can capture in a single image, usually expressed as width by height.

Example: Lowering the camera resolution from 1920x1080 to 640x480 helps a Pi 5 object-detection pipeline process more frames per second.

See also: Camera Module, Frame Capture

Camera Serial Interface¶

A dedicated connector on Raspberry Pi boards designed specifically for attaching an official camera module using a ribbon cable.

Example: A ribbon cable connects the Camera Module 3 to the Raspberry Pi 5's Camera Serial Interface connector, a dedicated port separate from the USB or GPIO pins.

See also: Camera Module

Camera To Model Pipeline¶

The specific sequence of steps that takes a raw frame from a camera module, prepares it, and feeds it into a machine learning model for inference.

Example: The chapter-17 camera-to-model pipeline captures a frame from the Pi Camera Module, resizes it, and feeds it into the Hailo accelerator for object detection.

See also: Image Preprocessing, Real Time Video Pipeline

Capacitor¶

An electronic component that stores electrical energy temporarily in an electric field and releases it, often used to smooth out sudden changes in voltage.

Example: A small capacitor placed near a motor driver helps smooth out voltage dips caused by the motor starting suddenly.

Capstone Project¶

A culminating project, typically completed near the end of a course, that requires students to combine multiple skills and concepts learned throughout the book.

Example: For their capstone project, a student combines skills from earlier chapters to build a voice-activated NeoPixel display that also logs sensor data over MQTT.

See also: Design Brief, Cross Tier Integration

Captive Portal¶

A web page that a network automatically displays to a newly connected device, often requiring login or agreement to terms before granting full internet access.

Example: A Pico W configured as a Wi-Fi access point shows a captive portal page asking a phone to enter Wi-Fi credentials before the device joins the home network.

See also: Access Point Mode

Case And Ventilation¶

The physical enclosure around a Raspberry Pi and the airflow design that allows heat generated by its chips to escape safely.

Example: The Pi 5 hardware chapter compares several case-and-ventilation designs, showing how airflow slots around the Active Cooler prevent thermal throttling during heavy AI workloads.

See also: Active Cooling, Thermal Throttling

Chained LED Protocol¶

A communication method used by addressable LEDs in which color data for the entire strip is sent as one continuous stream, with each LED reading and passing along only the portion meant for it.

Example: Because of the chained LED protocol, sending sixty color values down a single wire lights up sixty separate NeoPixels in order.

See also: WS2812B LED, Data Line

Change Directory Command¶

The Linux command, cd, used to move the shell's working directory to a different folder.

Example: A student types cd Documents/robot-code at the terminal to move into the folder holding their STEM robot's Python scripts.

See also: Working Directory

Chase Animation¶

A lighting pattern in which one or a few lit pixels appear to move continuously along a strip, as each frame shifts the lit position by one pixel.

Example: A NeoPixel strip project runs a chase animation where a single lit pixel appears to race down the strip, one position shifting per frame.

See also: Animation Frame, Sparkle Animation

Chassis Assembly¶

The step-by-step process of physically attaching motors, wheels, a battery holder, and mounting brackets to a robot's frame.

Example: The chapter-7 STEM robot build guide walks students through chassis assembly, attaching two motors, a battery holder, and caster wheel to the plastic frame with small screws.

See also: Robot Chassis

Chmod Command¶

A Linux command used to change a file or folder's file permissions, controlling who can read, write, or run it.

Example: A student runs chmod +x setup.sh in the terminal so their shell script can be executed directly instead of only being read.

See also: File Permissions

Chown Command¶

A Linux command used to change which user or group owns a particular file or folder.

Example: After copying project files from another user's account, a student uses the chown command to make their own account the owner of the files on their Pi 500+.

See also: File Permissions

Circuit Diagram¶

A visual representation of a circuit's physical wiring, often showing components in a layout close to how they would actually be placed on a breadboard.

Example: A circuit diagram for a button project shows the breadboard, the Pico, and jumper wires drawn in roughly their real positions.

Contrast with: Schematic Diagram

Class Label¶

The specific category name, such as "cat" or "stop sign," that a machine learning model assigns to an object or image during classification.

Example: The Pi 5 object-detection demo prints the class label "person" above each bounding box it draws around a detected human in the camera feed.

See also: Image Classification, Labeled Dataset

Classroom Budget¶

The total amount of money a teacher or program has available to purchase hardware, components, and supplies for a set of students over a school term.

Example: A classroom budget of five hundred dollars might stretch to cover twenty Pico breadboard kits but not twenty Raspberry Pi 5 setups.

See also: Project Budgeting

Classroom Kit Organization¶

The system used to sort, label, and store project components so that individual kits can be quickly distributed to and collected from students.

Example: A teacher labels 15 plastic bins, one per STEM robot kit, so classroom kit organization lets students grab and return their exact set of motors, wheels, and wires each session.

See also: Storage And Inventory, Kit Checklist

Classroom Time Management¶

Planning how class time is divided among instruction, hands-on building, testing, and cleanup so a project can be completed within available sessions.

Example: A lesson plan for the NeoPixel chapter allocates 10 minutes for wiring, 25 minutes for coding, and 10 minutes for cleanup as part of classroom time management.

See also: Lab Station Setup

Clock Speed¶

The rate at which a processor executes basic operations, usually measured in megahertz or gigahertz, indicating roughly how many instruction cycles it can perform each second.

Example: A Raspberry Pi 5 has a much higher clock speed than a Raspberry Pi Pico, letting it decode video far faster.

Clock Update Interval¶

The length of time a clock or watch program waits between refreshing its displayed time, balancing accuracy and readability against power use and processing load.

Example: A digital clock project refreshes its OLED display once per second as its clock update interval, since updating every millisecond would waste power without improving readability.

See also: Clock Speed

Cloud Versus Edge Processing¶

The comparison between analyzing sensor data on a remote server over the internet, called cloud processing, versus analyzing it locally on the device itself, called edge processing.

Example: The AI HAT+ chapter contrasts cloud versus edge processing by noting that a Pi 5 with a Hailo accelerator can classify a sound locally in milliseconds, without sending audio to a remote server at all.

See also: Edge AI, On Device Processing

Code Editor¶

A software application designed for writing and editing program source code, often including features like syntax highlighting and error checking.

Example: Students write their MicroPython scripts for the Pico in a code editor such as Thonny before uploading them to the board.

See also: VS Code On Pi

Coin Cell Battery¶

A small, flat, round battery commonly used to keep a real-time clock module running while the rest of a device is unpowered.

Example: A CR2032 coin cell battery keeps a DS3231 real-time clock module ticking accurately even when the wearable watch project it's part of is unplugged from USB power.

See also: Real Time Clock

Collision Avoidance¶

A robot behavior that changes the robot's motion, such as stopping or turning, to prevent it from hitting a detected obstacle.

Example: Collision avoidance code stops both motors the instant the ultrasonic sensor reports an object closer than 10 centimeters.

See also: Obstacle Detection

Color Fade¶

An animation technique in which an LED's color or brightness changes gradually over a series of frames rather than switching instantly.

Example: A color fade from red to blue on a NeoPixel passes smoothly through purple shades in between.

See also: Animation Frame

Color Gradient Effect¶

A lighting pattern that smoothly transitions color across a row or region of keys, rather than each key showing a flat, uniform color.

Example: A Pi 500+ keyboard lighting script applies a color gradient effect that fades smoothly from blue on the left side of the keyboard to purple on the right.

See also: Color Fade

Color Mixing¶

The process of combining different intensities of red, green, and blue light to produce other colors, such as combining full red and full green to make yellow.

Example: Color mixing full red and full blue on a NeoPixel produces magenta.

See also: RGB Color Model

Color Palette¶

A predefined, limited set of colors chosen to be used together in a project, often selected to look harmonious or to match a theme.

Example: A holiday-themed NeoPixel project might use a color palette limited to red, green, and white.

See also: RGB Color Model

Color Theory¶

The study of how colors relate to, mix with, and visually affect one another, used to make informed choices about combining colors in art and design.

Example: Applying color theory, a student chooses orange and blue for a NeoPixel display because they sit opposite each other on the color wheel and contrast strongly.

See also: Color Wheel

Color Wheel¶

A circular diagram arranging colors by hue in the order they appear in the visible spectrum, used to plan color combinations and animations.

Example: Sampling colors evenly around the color wheel produces the smooth, continuous rainbow seen in a rainbow cycle animation.

See also: Hue, Rainbow Cycle

Command Line Interface¶

A way of interacting with a computer by typing text commands rather than clicking graphical icons and menus.

Example: Instead of clicking icons, a student practicing Linux skills types ls and cd at a command line interface in a terminal window on the Pi 500+.

See also: Terminal Emulator, Shell

Community Showcase Event¶

A public event, such as a maker fair or open house, where students display and demonstrate their projects to family members and the broader community.

Example: A school hosts a community showcase event where families walk through the classroom to see students' NeoPixel art pieces and STEM robots in action.

See also: Project Demo Day

Companion Book Cross Reference¶

A pointer within this book directing a reader to a related project, explanation, or example found in one of its companion volumes.

Example: A sidebar in the wearables chapter includes a companion book cross reference, pointing readers to a deeper 3D-printing guide in a related volume for custom watch enclosures.

See also: Remix And Extend

Component Datasheet¶

A technical document published by a manufacturer that specifies a component's electrical characteristics, pin layout, and operating limits.

Example: A component datasheet for a DHT11 sensor lists its supply voltage range and the minimum delay required between readings.

See also: Vendor Documentation

Component Sourcing¶

The process of identifying where to purchase the specific parts needed for a project, considering factors like price, availability, and quality.

Example: Before ordering parts for 20 STEM robot kits, a teacher does component sourcing, comparing prices for TT motors and photoresistors across two electronics suppliers.

See also: Vendor Comparison, Bill Of Materials

Component Substitution¶

The practice of replacing a specified part in a project with a different but compatible part, often due to cost or availability.

Example: A teacher facing a supply chain shortage of one photoresistor model finds a component substitution with similar specifications from a different supplier.

See also: Hardware Compatibility

Computational Thinking¶

A problem-solving approach that breaks challenges into smaller parts, looks for patterns, focuses on essential details, and expresses a solution as a series of steps a computer or person can follow.

Computational thinking is the mental toolkit behind every project in this book, whether wiring a circuit or writing MicroPython code.

Example: Before wiring a robot, a student breaks "avoid obstacles" into smaller steps: read the distance sensor, compare it to a threshold, and turn if the value is too small.

See also: Decomposition, Abstraction, Pattern Recognition

Confidence Score¶

A number, usually between 0 and 1, that a machine learning model assigns to a prediction to indicate how certain it is that the prediction is correct.

Example: A sound-classification program only flags a "glass breaking" alert when the model's confidence score for that class exceeds 90 percent.

See also: Object Detection, Detection Threshold

Constraint Based Design¶

A design approach in which specific limits, such as budget, size, or available parts, shape and narrow the possible solutions to a problem.

Example: The capstone chapter challenges students with constraint-based design, requiring a working robot project built for under $25 in parts and completed within two class periods.

Contrast with: Open Ended Problem

See also: Design Brief

Continuity Test¶

A multimeter function that checks whether an unbroken electrical path exists between two points, usually indicated by a beep when the path is complete.

Example: A continuity test on a jumper wire that produces no beep reveals the wire is broken inside its insulation.

See also: Multimeter

Contrast Setting¶

A display configuration value that controls the difference in brightness between a screen's lit and unlit pixels.

Example: Lowering an OLED display's contrast setting can extend battery life slightly at the cost of a dimmer image.

Convolutional Neural Network¶

A type of neural network specially structured to recognize visual patterns like edges and shapes in images, making it well suited for image classification and object detection.

Example: The object-detection model running on the AI HAT+ is a convolutional neural network trained to recognize edges and shapes that add up to objects like cups or stop signs.

See also: Neural Network, Image Classification

Cooperative Multitasking¶

A programming approach in which multiple tasks take turns running for short periods, each one voluntarily yielding control so others can also make progress, without a true operating system scheduler.

Example: Cooperative multitasking lets a single-core microcontroller update a display animation, check sensors, and play a melody in quick succession within one main loop.

See also: Non Blocking Code

Copy File Command¶

The Linux command, cp, used to duplicate a file or folder from one location to another.

Example: A student runs cp robot_code.py backup_robot_code.py at the terminal to duplicate their working robot script before making risky changes.

Contrast with: Move File Command

Cost Per Student¶

A budgeting calculation that divides a project's total cost by the number of students it will serve, used to compare the affordability of different project options.

Example: A teacher calculates the cost per student for a NeoPixel unit by dividing the $450 total kit cost by 30 students, arriving at $15 each.

See also: Total Cost Of Ownership, Project Budgeting

Course Wrap Up Reflection¶

A concluding activity in which a student looks back across an entire course, summarizing key skills learned and how their thinking changed.

Example: At the end of the book's final chapter, students complete a course wrap-up reflection describing how their comfort with wiring and Python code changed from chapter 1 to the capstone.

See also: Project Reflection

Cron Job¶

A task scheduled to run automatically at specified times or intervals by the Linux cron scheduling service.

Example: A cron job set to run every morning at 8 AM automatically starts a data-logging script on a Raspberry Pi.

See also: Shell Script

Cross Compilation¶

The process of building a program on one type of computer so that it can run on a different type of computer or processor, such as building Raspberry Pi software on a laptop.

Example: A developer builds a MicroPython firmware image on a laptop through cross compilation so it can run on the Pico's much smaller RP2040 chip.

Cross Tier Integration¶

The combination of hardware from more than one price tier or product family, such as a Pico sensor node reporting to a Raspberry Pi 5, within a single project.

Example: A cross tier integration project uses a Pico W to send temperature readings to a Raspberry Pi 5, which logs and graphs the data.

See also: Sensor To Cloud Pipeline, Multi Board Communication

Current¶

The rate of flow of electric charge through a circuit, measured in amperes, representing how many electrons pass a point each second.

Example: A single NeoPixel LED can draw up to about 60 milliamps of current at full white brightness.

See also: Voltage, Resistance, Current Draw Per LED

Current Draw Per LED¶

The amount of electrical current a single addressable LED consumes, which varies with its brightness and color and is used to estimate total power needs for a strip.

Example: A single NeoPixel can draw roughly 20 milliamps per primary color channel at full brightness, informing the current draw per LED used in power budget calculations.

See also: Power Budget For LEDs

Current Limiting Resistor¶

A resistor placed in series with an LED specifically to reduce the current flowing through it to a safe level, preventing the LED from overheating and failing.

Example: A 220-ohm current limiting resistor is wired in series with a single LED on a breadboard project to keep it from burning out when connected to a Pico's 3.3V pin.

See also: Resistor, LED

Custom Bitmap Icon¶

A small, hand-designed image made of individual pixels, stored in a program and drawn to a display to represent an icon, symbol, or character.

Example: A custom bitmap icon of a small heart is drawn on the OLED display whenever the robot detects a gentle pat.

Custom Key Mapping¶

A configuration that changes which action or character is produced when a specific physical key is pressed, differing from the keyboard's default layout.

Example: A student sets up custom key mapping on their Pi 500+ so that pressing a spare function key launches their robot-control script instead of its default action.

See also: Macro Key

Custom Object Class¶

A new category added to an object detection model, beyond its original set of labels, so it can recognize an object specific to a particular project.

Example: A student adds a custom object class named "robot marker" so their model can detect a specially printed card used in a robotics game.

See also: Transfer Learning, Class Label

Custom Watch Strap¶

A wristband, often designed or 3D printed by a maker, that attaches a wearable electronics project to the wrist in place of a commercially manufactured strap.

Example: A student 3D prints a custom watch strap to attach their round-display wearable clock project to their wrist instead of buying a manufactured band.

See also: Wristband Mounting

CYW43 Chip¶

The specific wireless chip built into the Raspberry Pi Pico W that provides its Wi-Fi and Bluetooth Low Energy capability.

Example: The Pico W's onboard CYW43 chip is what lets a chapter-10 project connect to a home Wi-Fi network and publish sensor readings over MQTT.

See also: Raspberry Pi Pico W, Wireless Module

Damage And Repair Plan¶

A prepared procedure for how a classroom or program will handle broken components or boards, including whether to repair, replace, or retire them.

Example: A program's damage and repair plan specifies that a robot with a stripped motor gear gets repaired with spare parts from the shared bin rather than replacing the whole kit.

See also: Device Lifespan

Data Line¶

The single wire on an addressable LED strip that carries the digital signal specifying the color of every pixel in sequence.

Example: A break in the data line partway down a NeoPixel strip causes every pixel after that point to go dark or show random colors.

See also: Chained LED Protocol

Daylight Saving Time¶

A seasonal practice of shifting clocks forward or back by one hour, which a clock program may need to account for when calculating local time.

Example: A DS3231-based clock project includes code that adjusts for daylight saving time each spring so the displayed hour stays correct without the student manually resetting it.

See also: Time Zone Offset

DC Motor¶

A motor that converts direct current electrical energy into continuous rotational motion, commonly used to drive a robot's wheels.

Example: Reversing the polarity of the voltage applied to a DC motor makes it spin in the opposite direction.

See also: Motor Polarity, Motor Driver

Debounce¶

A technique, implemented in hardware or software, that filters out the rapid, unintended on-off flickering a mechanical switch produces the instant it is pressed or released.

Example: Without debounce code, a single press of a push button might be read by the program as three or four separate presses.

See also: Push Button, Button Debounce Code

Debugging¶

The process of finding and fixing errors, called bugs, in a program or circuit so that it behaves as intended.

Example: When a NeoPixel strip stays dark, debugging might involve checking the data pin wiring, then the code, then the power supply, one step at a time.

See also: Root Cause Analysis, Rubber Duck Debugging

Decomposition¶

The practice of breaking a complex problem or system into smaller, more manageable parts that can be understood, built, and tested individually.

Example: A wearable clock project is decomposed into separate parts: reading the real-time clock module, formatting the time as text, and drawing that text on the display.

Deep Sleep¶

A very low power state in which a microcontroller shuts down nearly all its circuitry, saving significantly more energy than sleep mode but typically taking longer to wake and resume normal operation.

Example: A battery-powered wearable watch drops into deep sleep between button presses, waking only briefly every minute to refresh its round display and conserve the coin cell battery.

Contrast with: Sleep Mode

See also: Low Power Design

Design Brief¶

A short written description of a project's goals, constraints, and requirements, used to guide planning before building begins.

Example: Before building their capstone project, a student writes a one-page design brief describing the problem their NeoPixel-and-sensor device will solve and what parts it needs.

See also: Capstone Project, Requirements Gathering

Desktop Environment¶

The graphical interface of an operating system, including its windows, icons, taskbar, and menus, that lets a user interact with the computer visually rather than through text commands alone.

Example: After booting, the Raspberry Pi 500+ shows a full desktop environment with a taskbar, file manager icon, and application menu, similar to a traditional laptop.

See also: Window Manager, Raspberry Pi OS

Detection Threshold¶

A minimum confidence score a machine learning model's prediction must reach before a program treats it as a valid detection.

Example: Raising the detection threshold from 0.5 to 0.8 makes an object detector report fewer, but more certain, detections.

See also: Confidence Score

Device Lifespan¶

The length of time a piece of hardware remains functional and useful before it wears out, becomes obsolete, or is no longer supported.

Example: A well-cared-for Raspberry Pi Pico can have a device lifespan of many years, since it has no moving parts to wear out.

Device Tree Overlay¶

A configuration file that describes additional or modified hardware, such as a display or sensor, to the Linux kernel without changing the main system files.

Example: Enabling an SPI-connected TFT display on a Raspberry Pi sometimes requires adding a device tree overlay line to a configuration file so Linux recognizes the new hardware.

See also: Kernel Driver

DHCP¶

Dynamic Host Configuration Protocol, a system used by a router or network to automatically assign an IP address to a device when it joins the network.

Example: When a Pico W joins a classroom Wi-Fi network, DHCP automatically assigns it an IP address like 192.168.1.42 without the student typing one in manually.

See also: IP Address

DHT11 Sensor¶

A low-cost sensor module that measures both temperature and relative humidity and reports both values over a single digital data line.

Example: A DHT11 sensor connected to a Pico reports that the classroom is 22 degrees Celsius and 45 percent humidity.

See also: Temperature Sensor, Humidity Sensor

Differential Drive¶

A robot movement design in which two independently controlled wheels, one on each side, are used to move forward, backward, and turn by varying their relative speeds.

Example: In differential drive, spinning the right wheel faster than the left wheel curves the robot's path to the left.

See also: Left Motor, Right Motor, Turning Radius

Differentiated Instruction¶

A teaching approach that adjusts the complexity, pacing, or support of a lesson to meet the varying needs and skill levels of individual students.

Example: A teacher uses differentiated instruction by offering an optional extension challenge for the NeoPixel chapter to students who finish the base rainbow-cycle project early.

See also: Group Size Planning

Digital Audio Signal¶

A sound represented as a sequence of discrete numeric values, produced by sampling an analog audio signal at regular intervals.

Example: After the microphone's analog output is sampled, the Pi 5's sound card stores it as a digital audio signal, a stream of numbers the sound-classification model can process.

Contrast with: Analog Audio Signal

See also: Audio Sampling Rate

Digital Clock Format¶

A way of displaying the current time as numeric digits, such as hours and minutes separated by a colon, rather than as rotating hands on a dial.

Example: A seven-segment display project shows the time in digital clock format as "14:07" rather than drawing analog clock hands.

Contrast with: Analog Clock Hands

See also: Time Formatting Code

Digital Input¶

A GPIO pin operating mode in which a microcontroller reads whether an external voltage on the pin is currently high or low.

Example: A button wired to a pin configured as digital input lets code check whether the button is currently pressed.

Contrast with: Digital Output

Digital Output¶

A GPIO pin operating mode in which a microcontroller actively sets a pin to a high or low voltage to control an external device.

Example: Setting a pin to digital output and writing a high value turns on an LED connected to that pin.

Contrast with: Digital Input

Digital Pin¶

A GPIO pin configured to read or write only one of two states, typically represented as on or off, high or low, corresponding to roughly 3.3 volts or 0 volts.

Example: A digital pin set to output high turns an LED fully on; set to low, it turns the LED fully off.

Contrast with: Analog Pin

Digital Read¶

An operation that checks whether a digital pin currently reads a high or low voltage and returns that as an on or off value.

Example: A digital read of a button pin returns a low value the instant the button is pressed, if wired with a pull up resistor.

Contrast with: Analog Read

Display Refresh¶

The act of sending an updated pixel buffer or frame buffer to a physical display so the new image actually appears on screen.

Example: A watch face project calls a display refresh function every second, pushing the updated pixel buffer to the round TFT screen so the new time actually appears.

See also: Frame Buffer, Non Blocking Code

Display Resolution¶

The number of individual pixels a screen contains, usually expressed as width by height, which determines how much detail it can show.

Example: A small OLED display resolution of 128 by 64 pixels is enough to draw simple robot eyes and short text.

See also: OLED Display, Pixel Buffer

Display Wiring¶

The specific set of connections, such as power, ground, and data lines, required to connect a display module to a microcontroller's GPIO or I2C pins.

Example: The chapter-9 clock project's display wiring connects the SSD1306 OLED's SDA and SCL pins to the Pico's I2C pins, along with power and ground.

See also: I2C Protocol, SPI Protocol

Distance Measurement¶

The process of determining how far away an object is, typically performed using an ultrasonic or time of flight sensor mounted on a robot.

Example: A STEM robot performs distance measurement with its ultrasonic sensor, reading how many centimeters away a wall is before deciding to turn.

See also: Ultrasonic Sensor, Obstacle Detection

Donor Sourced Hardware¶

Equipment obtained through donations from individuals or organizations rather than through a direct classroom purchase.

Example: A robotics club builds part of its NeoPixel unit using donor-sourced hardware after a local business donates a box of surplus breadboards and jumper wires.

See also: Grant Funding

Draw Circle¶

A graphics operation that sets a ring or filled area of pixels forming a circle at a specified center point and radius on a display's pixel buffer.

Example: A round watch face script calls a draw circle function to render the outer clock ring on the GC9A01 display before adding hour markers.

See also: Draw Line, Eye Shape

Draw Line¶

A graphics operation that sets a straight sequence of pixels between two points on a display's pixel buffer.

Example: An analog watch face project uses a draw line function to render the hour and minute hands, recalculating their endpoints every second.

See also: Draw Pixel, Draw Circle

Draw Pixel¶

A graphics operation that sets the color or on-off state of a single point on a display's pixel buffer.

Example: The SSD1306 OLED library's draw pixel function turns on a single dot in the frame buffer, the basic operation every other shape in an OLED robot face is built from.

See also: Pixel Buffer, Draw Line

Draw Text¶

A graphics operation that renders a string of characters onto a display's pixel buffer using a predefined font.

Example: A digital clock project calls a draw text function to render "10:45" in a chosen font onto the LCD1602's character grid.

See also: Font Rendering

DS3231 Module¶

A commonly used real-time clock module known for its high timekeeping accuracy, communicating with a microcontroller over the I2C protocol.

Example: A wristwatch project uses a DS3231 module wired over I2C to keep accurate time even when the Pico is disconnected from USB power.

See also: Real Time Clock, I2C Protocol

Dual 4K Display Output¶

A Raspberry Pi 5 capability that allows two separate high-resolution monitors to be connected and driven at the same time.

Example: A student uses the Raspberry Pi 5's dual 4K display output to run code on one monitor while watching a live camera feed from the object-detection project on the other.

Duty Cycle¶

The percentage of time a PWM signal spends in the high, or on, state during each repeating cycle, which determines the effective average power delivered.

Example: Setting an LED's duty cycle to 25 percent makes it appear noticeably dimmer than a duty cycle of 90 percent.

See also: PWM

Edge AI¶

The practice of running machine learning inference directly on a local device, such as a Raspberry Pi 5, rather than sending data to a remote server for processing.

Example: Running a sound-classification model directly on the Pi 5's Hailo accelerator, without any internet connection, is an example of edge AI described in chapter 16.

Contrast with: Cloud Versus Edge Processing

See also: Model Compression, Inference Latency

Edge Case¶

An unusual or extreme input or situation that a program or circuit must still handle correctly, even though it falls outside typical, everyday conditions.

Example: A distance-sensing robot must handle the edge case of a sensor reading of zero, which could mean an object is touching the sensor or that the sensor lost its connection.

Electrical Safety¶

Practices that reduce the risk of shock, burns, or fire when working with circuits, wiring, and powered components.

Example: The breadboard chapter's electrical safety section reminds students to double-check polarity before connecting a battery pack, since reversing it can damage an LED or Pico.

See also: Safety Guidelines, Static Discharge

Emergency Stop Button¶

A dedicated, easily accessible button that immediately cuts power to a robot's motors when pressed, used as a safety measure during testing.

Example: A STEM robot kit includes an emergency stop button wired to cut motor power instantly if the robot starts driving toward a table edge during testing.

See also: Robot Safety Stop, Electrical Safety

Emotion State¶

A named condition, such as "happy" or "curious," that determines which facial expression, sound, or lighting behavior a robot currently displays.

Example: An OLED-equipped robot switches its emotion state from "neutral" to "surprised" the instant its ultrasonic sensor detects a sudden nearby obstacle.

See also: Facial Expression Design, State Machine

Engineering Design Process¶

A repeating cycle of defining a problem, brainstorming solutions, building a prototype, testing it, and improving the design based on results.

Example: The capstone chapter walks students through the engineering design process: defining a problem, sketching ideas, building a NeoPixel prototype, testing it, then refining the code.

See also: Iterative Design, Requirements Gathering

Environment Variable¶

A named value stored by the operating system that programs can read to configure their behavior, such as a default folder location or a system setting.

Example: A Pi 5 Python script reads an environment variable to find the Wi-Fi network name instead of hard-coding it directly into the source file.

See also: Shell Script

Environmental Sound Class¶

A category of everyday, non-speech sound, such as a smoke alarm or breaking glass, that a sound classification model is trained to recognize.

Example: The chapter-18 sound classifier is trained to recognize environmental sound classes such as a smoke alarm, doorbell, and dog bark from a microphone feed.

See also: Sound Classification, Alert Sound Trigger

Epoch Time¶

A way of representing a specific moment in time as a single number counting the seconds that have elapsed since a fixed reference point, commonly midnight January 1, 1970.

Example: A clock program converts epoch time into readable hours, minutes, and seconds before drawing them on the display.

See also: Time Formatting Code

Event Driven Lighting¶

A keyboard lighting design in which color changes are triggered directly by specific events, such as a key press or an incoming notification, rather than running on a fixed timer.

Example: A Pi 500+ keyboard script uses event-driven lighting, flashing the Enter key gold the instant it detects a key-press event rather than running on a repeating timer.

See also: Event Driven Programming, Reactive Lighting

Event Driven Programming¶

A programming style in which the flow of a program is determined by events, such as a button press or an incoming message, rather than by a fixed, top-to-bottom sequence of steps.

Example: A keyboard lighting script that changes a key's color the instant that key is pressed, rather than checking it on a schedule, is event driven.

Contrast with: Polling

Expression Transition¶

The gradual or scripted change from one facial expression to another on a robot's display, rather than an instant, jarring switch.

Example: An OLED robot face gradually morphs its eye shape from neutral to happy over half a second, an expression transition that avoids an abrupt, jarring switch.

See also: Facial Expression Design, Emotion State

Eye Shape¶

A simple graphical element, often drawn as a circle, oval, or arc, used to represent a robot's eyes and convey an emotional state on a small display.

Example: Drawing an eye shape as a wide circle can represent surprise, while a thin horizontal line can represent a sleepy or closed eye.

See also: Facial Expression Design, Blink Animation

Facial Expression Design¶

The process of planning how a robot's simple graphical face, such as its eye shapes, should change to represent different emotions or states.

Example: In the OLED chapter, students sketch facial expression design options for their robot, deciding how eye width and mouth curve should represent "curious" versus "sleepy."

See also: Eye Shape, Emotion State

False Negative¶

An error in which a machine learning model fails to detect something that is actually present or true.

Example: An object-detection model producing a false negative might fail to draw a bounding box around a person standing in a dim corner of the frame.

Contrast with: False Positive

False Positive¶

An error in which a machine learning model reports that something is present or true when it is actually not.

Example: A sound-recognition system producing a false positive might flag ordinary background noise as a wake word.

Contrast with: False Negative

Fast Fourier Transform¶

A mathematical algorithm that converts a sound signal from a sequence of amplitude values over time into a breakdown of the frequencies present within it.

Example: The audio-classification pipeline applies a Fast Fourier Transform to a captured clip to reveal which frequencies are present before feeding that data into the sound model.

See also: Frequency Spectrum, Spectrogram

Feedback Loop¶

A repeating cycle in which a system's output is measured and used to adjust its next action, allowing the system to respond to changing conditions.

Example: A line-following robot forms a feedback loop by continuously reading its reflectance sensors and adjusting motor speed based on whether it is drifting off the line.

See also: Sense Think Act Cycle

File Manager¶

A graphical application that lets a user browse, open, move, copy, and delete files and folders without typing commands.

Example: A student drags a photo from the desktop into their project folder using the Raspberry Pi OS file manager instead of typing a copy command in the terminal.

Contrast with: Terminal Emulator

File Permissions¶

Settings attached to every file and folder on a Linux system that control which users are allowed to read, write, or execute it.

Example: A shell script for automating robot startup won't run until a student adjusts its file permissions with chmod +x to mark it executable.

See also: Chmod Command, Chown Command

File System Hierarchy¶

The nested, tree-like arrangement of folders and files that organizes all the data stored on a Linux computer, starting from a single root folder.

Example: A student learns the Linux file system hierarchy by tracing the path from the root folder down to their own project files inside /home/pi/robot-code.

See also: Root User, Home Directory

File Transfer Protocol¶

A standard method for copying files between two computers over a network, one of several ways to move files onto or off of a Raspberry Pi.

Example: A student uses File Transfer Protocol software to move a finished MicroPython script from a laptop onto a Pico connected over USB.

Fill Method¶

A function provided by an LED control library that sets every pixel in a strip to the same specified color in a single call.

Example: Calling the fill method with the color blue turns an entire NeoPixel strip blue at once, without looping through each pixel manually.

See also: Set Pixel Color

Firewall Basics¶

Fundamental rules and concepts governing how a firewall filters incoming and outgoing network traffic to block unwanted or unsafe connections.

Example: The networking chapter covers firewall basics so students understand why a Pi 5 running an MQTT broker should only accept connections from devices on the classroom's own network.

See also: Network Security

Flowchart¶

A diagram that uses standardized shapes and connecting arrows to show the order of steps, decisions, and branches in a process or algorithm.

Example: A flowchart for a robot's obstacle-avoidance behavior shows a diamond-shaped decision box asking "Is an object closer than 10 cm?" with separate arrows for yes and no.

See also: Pseudocode, Algorithm

Font Rendering¶

The process of converting text characters into the specific pattern of pixels needed to display them on a screen, based on a stored font design.

Example: The LCD1602 library performs font rendering to convert the text "12:00" into the specific pixel pattern the character display can show.

See also: Draw Text

Forward Motion¶

The movement of a robot in the direction its front is facing, produced by driving both the left and right motors at matching speed in the same rotational direction.

Example: A STEM robot achieves forward motion by driving both its left and right TT motors at the same PWM speed in the same rotational direction.

Contrast with: Turning Radius

Forward Voltage¶

The minimum voltage required across an LED, in its correct polarity, before it begins to conduct current and emit light.

Example: A typical red LED has a forward voltage of about 2 volts, while a blue LED may need closer to 3 volts.

See also: LED, LED Polarity

Frame Buffer¶

A complete pixel buffer representing one full image or frame, held in memory and transmitted to a display to update what is shown all at once.

Example: An OLED robot-face program draws an entire eye shape into a frame buffer in memory, then sends the whole buffer to the SSD1306 display in one update so the change appears instantly.

See also: Pixel Buffer, Display Refresh

Frame Capture¶

The act of recording a single still image from a camera's continuous video feed at a specific moment in time.

Example: The Pi 5 object-detection script performs frame capture, grabbing a single still image from the Camera Module's live video feed every time it needs to run inference.

See also: Video Stream, Camera Module

Frame Rate¶

The number of animation frames displayed per second, which determines how smooth motion or change appears to a viewer.

Example: Increasing a NeoPixel animation's frame rate from 10 to 30 frames per second makes a chase effect look noticeably smoother.

See also: Animation Frame

Frames Per Second¶

A measurement of how many individual video frames a camera or a machine learning pipeline can capture or process each second.

Example: A chapter-17 object-detection demo processes about 20 frames per second on the Hailo accelerator, fast enough to track a moving hand smoothly.

See also: Frame Rate, Inference Latency

Frequency Spectrum¶

A representation of a sound showing how much energy it contains at each frequency, typically produced using a Fast Fourier Transform.

Example: The chapter-18 audio pipeline plots a frequency spectrum of a captured clip to show that a smoke alarm's energy is concentrated around 3,000 Hz, distinct from the lower-pitched hum of a doorbell.

See also: Fast Fourier Transform, Spectrogram

Game Status Indicator¶

A lighting effect that maps a game's in-progress state, such as remaining health or ammunition, onto a keyboard's RGB keys in real time.

Example: A Pi 500+ lighting script turns the WASD keys from green to red as a game status indicator showing a player's health draining during a coding game.

See also: Per Key RGB Lighting

GC9A01 Driver¶

A common controller chip used in small round TFT display modules, popular for building round watch face projects.

Example: A round wristwatch project uses the GC9A01 driver chip to control its circular TFT display over the SPI protocol.

See also: Round Display, TFT Display

Gigabit Ethernet¶

A wired networking connection capable of transferring data at up to one billion bits per second, providing a faster and more reliable connection than typical Wi-Fi.

Example: A student connects their Raspberry Pi 5 to a classroom router with an Ethernet cable to get a more reliable Gigabit Ethernet connection than Wi-Fi during a live camera-streaming demo.

Git Basics¶

The fundamental commands and concepts of Git, a widely used version control system, including saving changes as commits and tracking a project's history.

Example: A student learns Git basics by committing their NeoPixel project code after each working feature, building a saved history they can revert to if a later change breaks it.

See also: Version Control, GitHub Repository

GitHub Repository¶

An online storage location that hosts a project's files and their complete Git version history, allowing sharing and collaboration over the internet.

Example: A class publishes its finished capstone projects to a shared GitHub repository so students can browse each other's code after Demo Day.

See also: Git Basics

Global Shutter Camera¶

A camera design that captures every pixel of an image at exactly the same instant, avoiding distortion when photographing fast-moving objects.

Example: A global shutter camera module would be preferred over a standard rolling shutter one for a chapter-17 project tracking a fast-spinning robot wheel without visible warping.

Contrast with: Rolling Shutter Camera

GPIO Header¶

The full row of GPIO pins physically arranged on a Raspberry Pi board, providing access to multiple digital, power, and ground connections at once.

Example: The 40-pin GPIO header on a Raspberry Pi 5 provides the power, ground, and digital pins used to wire an external NeoPixel strip directly to the board.

See also: 40 Pin Header, GPIO Pin

GPIO Pin¶

A General Purpose Input/Output pin on a microcontroller or single board computer that software can configure to either read an incoming signal or send an outgoing signal.

Example: GPIO pin 15 on a Raspberry Pi Pico is configured as a digital output to control an LED.

See also: Digital Pin, Analog Pin, Pin Numbering

Grant Funding¶

Money awarded by an organization, often without requiring repayment, to support the purchase of educational hardware or materials.

Example: A teacher applies for grant funding from a local STEM foundation to cover the cost of 25 STEM robot kits for next year's class.

See also: Donor Sourced Hardware, Project Budgeting

Ground¶

The common reference point in a circuit, usually at zero volts, to which all voltage measurements are compared and through which current returns to its source.

Example: Every component on a breadboard circuit shares a connection back to the Pico's ground pin so current can complete its path.

See also: VCC, Short Circuit

Group Size Planning¶

Deciding how many students should work together at each lab station based on the project's complexity, available equipment, and learning goals.

Example: For the wiring-heavy breadboard chapter, a teacher's group size planning limits stations to two students per kit so everyone gets hands-on time.

See also: Lab Station Setup, Differentiated Instruction

H Bridge¶

A motor driver circuit configuration that uses four switches arranged in an H shape to control both the direction and speed of a DC motor's rotation.

Example: An H bridge lets a single motor driver chip spin a wheel forward, spin it backward, or stop it, all from the same two control pins.

See also: Motor Driver, Motor Polarity

Hailo Accelerator¶

The specific neural processing chip used on the AI HAT+ add-on board to run machine learning inference efficiently alongside a Raspberry Pi 5.

Example: The AI HAT+ add-on board plugs into a Raspberry Pi 5 and uses its Hailo accelerator chip to run the object-detection model far faster than the Pi's CPU alone could.

See also: AI HAT Plus, Hardware Accelerator

Hardware Accelerator¶

A specialized chip designed to perform a specific type of computation, such as neural network math, far more efficiently than a general-purpose processor.

Example: The Hailo chip on the AI HAT+ is a hardware accelerator specifically built to speed up the matrix math used in neural-network inference.

See also: Neural Processing Unit, Hailo Accelerator

Hardware Compatibility¶

The degree to which a component, accessory, or software tool will work correctly with a specific board, considering factors like voltage, connector type, and driver support.

Example: Checking hardware compatibility before buying a camera module confirms it uses the same Camera Serial Interface connector as the Raspberry Pi 5.

74HC595 Chip¶

A specific, widely used shift register chip that expands a microcontroller's limited number of output pins into eight additional digital outputs.

Example: A project driving eight LEDs from just three Pico pins uses a 74HC595 chip as a shift register to expand the available outputs.

See also: Shift Register

Headless Setup¶

Configuring and operating a Raspberry Pi without connecting a monitor, keyboard, or mouse directly to it, typically managed instead over SSH or Wi-Fi.

Example: A student configures their Raspberry Pi 5 for a headless setup, connecting over SSH from a laptop instead of plugging in a monitor and keyboard directly.

See also: SSH Protocol, Remote Login

Heat Sink¶

A metal component attached to a chip that absorbs and spreads heat away from it, increasing the surface area available for that heat to dissipate into the air.

Example: A small heat sink glued to the Raspberry Pi 5's BCM2712 chip helps spread heat away during a long-running AI HAT+ object-detection session.

Contrast with: Active Cooling, which adds a fan; a heat sink alone works passively.

See also: Active Cooling

Home Directory¶

The personal folder assigned to a specific user account, where that user's own files and settings are normally stored.

Example: All of a student's Python scripts for the robot project are saved inside their home directory, /home/pi, on the Raspberry Pi OS file system.

See also: File System Hierarchy, Working Directory

Hostname¶

A human-readable name assigned to a computer on a network, used in place of its numeric IP address to identify and reach it.

Example: Typing raspberrypi.local as a hostname lets a user connect over SSH without knowing the Pi's exact IP address.

See also: IP Address, Local Network Discovery

HTTP Protocol¶

Hypertext Transfer Protocol, a standard set of rules that web browsers and servers use to request and deliver information over a network.

Example: A Pico W web-control project uses the HTTP protocol to let a browser on a phone request a page that shows the robot's current sensor readings.

See also: HTTP Request, HTTP Response, Web Server

HTTP Request¶

A message sent by a client, such as a web browser or a Pico W, asking a web server for information or asking it to perform an action.

Example: Clicking a "Lights On" button in a browser sends an HTTP request to a Pico W's built-in web server, asking it to turn on a connected NeoPixel strip.

Contrast with: HTTP Response

See also: HTTP Protocol, REST Endpoint

HTTP Response¶

The message a web server sends back after receiving an HTTP request, typically containing the requested data or a status indicating success or failure.

Example: After receiving a command, the Pico W's web server sends back an HTTP response confirming the NeoPixel strip was successfully turned on.

Contrast with: HTTP Request

See also: HTTP Protocol

Hue¶

The attribute of a color that describes its position on the color wheel, such as red, orange, yellow, or blue, independent of how light, dark, or vivid it appears.

Example: Rotating through hue values from 0 to 360 while keeping saturation and brightness fixed produces a smooth rainbow animation.

See also: Saturation, Brightness, Color Wheel

Human Interface Device¶

A category of hardware, including keyboards and mice, designed to let a person directly interact with a computer through the USB HID protocol.

Example: The Raspberry Pi 500+'s built-in keyboard identifies itself to the operating system as a Human Interface Device, the same USB category as an external mouse.

See also: USB HID Protocol

Humidity Sensor¶

A sensor that measures the amount of water vapor present in the surrounding air, usually expressed as a percentage of relative humidity.

Example: A weather-station project adds a humidity sensor alongside a temperature sensor so a Pico W can log both readings and publish them over MQTT.

See also: DHT11 Sensor

I2C Address¶

A unique numeric identifier assigned to a device on an I2C bus, allowing a microcontroller to direct commands to that specific device even though multiple devices share the same wires.

Example: An SSD1306 OLED display commonly uses the I2C address 0x3C.

See also: I2C Protocol

I2C Protocol¶

A two-wire communication standard that lets a microcontroller exchange data with one or more peripheral chips, such as displays or sensors, each identified by its own address.

Example: An OLED display and a real-time clock module can share the same two I2C protocol wires because each has a different I2C address.

Contrast with: SPI Protocol

See also: I2C Address

I2S Audio Interface¶

A digital audio communication standard used to transmit sound data between a microcontroller or computer and an audio chip, such as a DAC or microphone.

Example: A chapter-18 sound project connects a PCM5102 DAC to a Pico using the I2S audio interface to output clean digital audio to a speaker.

See also: PCM5102 DAC

Idle Animation¶

A looping animation played on a robot's display or lights while it is not actively responding to a sensor event, used to show the robot is powered on and active.

Example: An OLED-equipped robot plays a slow blinking idle animation on its face whenever no obstacle or sound has triggered a reaction recently.

See also: Blink Animation, Animation Timing

ILI9341 Driver¶

A common controller chip used in rectangular TFT display modules that manages the pixel data sent from a microcontroller over the SPI protocol.

Example: A rectangular TFT display used in a digital clock project relies on the ILI9341 driver chip to receive pixel data from the Pico over SPI.

See also: TFT Display, SPI Protocol

Image Classification¶

A machine learning task in which a model assigns a single label describing the overall content of an entire image.

Example: A Pi 5 project performs image classification by labeling an entire photo "cat" versus "not cat," without marking where in the image the cat actually is.

Contrast with: Object Detection, which locates multiple objects rather than labeling the whole image.

See also: Class Label, Convolutional Neural Network

Image Preprocessing¶

The steps applied to a raw camera image, such as resizing or adjusting brightness, before it is fed into a machine learning model for inference.

Example: Before running a captured frame through the object-detection model, the chapter-17 pipeline performs image preprocessing, resizing it to the exact input dimensions the model expects.

See also: Region Of Interest, Camera To Model Pipeline

Image Sensor¶

The electronic component inside a camera module that converts incoming light into digital pixel data.

Example: Inside the Camera Module 3, the image sensor converts incoming light into the digital pixel data that becomes each captured video frame.

See also: Camera Module, Rolling Shutter Camera

Independent Study Extension¶

An optional, self-directed project or set of challenges that lets a student go beyond a chapter's core content on their own.

Example: After finishing the NeoPixel chapter, a motivated student pursues an independent study extension, building an audio-reactive light show driven by a microphone.

See also: Next Steps Learning Path

Inference Latency¶

The amount of time that passes between feeding input into a machine learning model and receiving its output prediction.

Example: The AI HAT+ reduces inference latency enough that a Pi 5 object-detection demo can label a detected object within about 50 milliseconds of capturing the frame.

See also: Model Inference, Frames Per Second

Infrared Sensor¶

A sensor that detects infrared light, either emitted by a warm object or reflected from an emitter on the sensor itself, commonly used for proximity or line detection.

Example: A line-following STEM robot uses infrared sensors mounted on its underside to detect the reflectance difference between a black line and the light-colored floor.

See also: Reflectance Sensor

Input Device¶

A component that captures information from the physical world or a user and converts it into a signal a computer or microcontroller can read.

Example: A push button, a photoresistor, and a microphone are all input devices used in this book's projects.

Contrast with: Output Device

Install Package Command¶

The command, typically sudo apt install, used with the APT package manager to download and set up a new piece of software.

Example: A student runs the install package command sudo apt install mosquitto to add an MQTT broker to their Raspberry Pi.

See also: APT Package Manager, Sudo Command

Interrupt¶

A signal that pauses a microcontroller's normal program execution so it can immediately run a small block of code in response to an event, then resume where it left off.

Example: A button wired to trigger an interrupt lets a robot stop instantly when pressed, without waiting for the main loop to check the button's state.

Contrast with: Polling

Interrupt Handler¶

A dedicated block of code that a microcontroller runs automatically whenever a specific interrupt event occurs, then returns control to the main program.

Example: An interrupt handler attached to a button pin immediately sets a flag variable the instant the button is pressed, even mid-loop.

See also: Interrupt

IP Address¶

A numeric identifier assigned to a device connected to a network, used to route data to and from that specific device.

Example: A Pico W is assigned an IP address by the home router after joining the Wi-Fi network, letting a web browser reach its web server.

See also: DHCP

Iterative Design¶

A development approach in which a project is repeatedly built, tested, evaluated, and improved in successive rounds rather than being finished in a single attempt.

Example: A wearable watch case is redesigned three times, each version fixing a fit or wiring problem found during testing on the previous prototype.

See also: Prototype, Prototype Iteration

JSON Data Format¶

A lightweight, text-based format for structuring data using nested labels and values, commonly used to exchange information between devices and web services.

Example: A weather web service returns the current temperature to a Pico W in JSON data format, which the program then parses into a usable number.

See also: REST Endpoint

Jumper Wire¶

A short, flexible wire with a connector on each end used to make electrical connections between points on a breadboard, GPIO header, or component.

Example: A jumper wire carries the signal from a Pico's GPIO pin to a push button on the breadboard.

Kernel Driver¶

A piece of software loaded into the Linux kernel that allows the operating system to communicate with a specific piece of hardware, such as a camera or display.

Example: Enabling the Camera Module on a Raspberry Pi 5 loads a kernel driver that lets Linux recognize and read frames from the camera hardware.

See also: Linux Kernel, Device Tree Overlay

Key Press Event¶

A notification generated the moment a key is physically pushed down, which a program can detect and respond to.

Example: A Pi 500+ lighting script listens for a key press event on the spacebar and immediately flashes it white before returning to its normal color.

Contrast with: Key Release Event

Key Release Event¶

A notification generated the moment a previously pressed key is let go, which a program can detect and respond to.

Example: A typing-speed keyboard-lighting project measures the time between a key press event and the following key release event to estimate how fast a student is typing.

Contrast with: Key Press Event

Key Scan Code¶

A numeric code generated by a keyboard's controller identifying exactly which physical key was pressed or released, before it is translated into a letter or symbol.

Example: The Pi 500+'s keyboard firmware reports a raw key scan code for the "A" key before the operating system translates it into the letter "a."

See also: Keyboard Matrix, Keyboard Firmware

Keyboard API¶

A programming interface that lets software detect key press and release events and, on supported keyboards, control per-key lighting.

Example: A Python script uses the Pi 500+'s keyboard API to detect that the Enter key was pressed and to set that key's RGB zone to green.

See also: Python Keyboard Library

Keyboard Backlight Brightness¶

A setting that controls the overall light output level of a keyboard's RGB lighting, independent of the specific colors displayed.

Example: A student lowers the keyboard backlight brightness on their Pi 500+ during a late-night coding session to avoid glare, without changing any of the chosen colors.

See also: Brightness

Keyboard Firmware¶

The low-level software running inside a keyboard's own controller chip that reads the key matrix and, on RGB models, drives the per-key lighting.

Example: The Raspberry Pi 500+'s keyboard firmware continuously scans its key matrix and updates per-key RGB colors even before any Python script runs.

See also: Keyboard Matrix, Per Key RGB Lighting

Keyboard Matrix¶

The internal grid wiring arrangement used inside a keyboard that lets its controller detect which specific key has been pressed or released.

Example: Inside the Pi 500+, the keyboard matrix wiring lets the controller determine that the key at row 3, column 5 was pressed rather than reading each of 80-plus keys on its own wire.

See also: Key Scan Code, Keyboard Firmware

Keyboard Shortcut¶

A combination of keys pressed together that triggers a specific software command or action, rather than typing a character.

Example: Pressing Ctrl+C in a terminal window is a keyboard shortcut students use to stop a runaway Python script on their Raspberry Pi.

See also: Custom Key Mapping

Keyword Spotting¶

A specialized form of sound classification that continuously listens for one or a small number of specific spoken words or phrases.

Example: A voice-controlled NeoPixel project uses keyword spotting to continuously listen for the single word "lights" before waking up to process a fuller voice command.

See also: Wake Word Detection

Kit Checklist¶

A list used to verify that every required component is present in a project kit before it is distributed or returned.

Example: Before handing out STEM robot kits, a teacher runs down a kit checklist confirming each box has two motors, a Pico, a battery holder, and all its screws.

See also: Classroom Kit Organization

Lab Station Setup¶

The physical arrangement of tools, components, and workspace at each student or group location to support building and testing a project.

Example: The breadboard chapter recommends a lab station setup with a breadboard, jumper wire bin, and multimeter placed at each pair of seats before class starts.

See also: Group Size Planning

Labeled Dataset¶

A collection of example data, such as images, in which each item has been tagged with its correct answer, used to train or evaluate a machine learning model.

Example: The chapter-16 image-classification example uses a labeled dataset of photos, each tagged "dog," "cat," or "neither," to train and test a simple model.

See also: Training Dataset, Class Label

LCD Character Display¶

A liquid crystal display module designed to show only fixed-width text characters, arranged in a small grid of rows and columns, rather than freeform graphics.

Example: An LCD1602 module is an LCD character display used in a chapter-9 clock project to show digits and text but not custom graphics or shapes.

See also: LCD1602 Module

LCD1602 Module¶

A common LCD character display capable of showing sixteen characters across two rows of text, often connected over the I2C protocol.

Example: A digital clock project connects an LCD1602 module over I2C to show the current time as two rows of sixteen characters.

See also: LCD Character Display, I2C Protocol

Lead Time¶

The amount of time that passes between placing an order for a component and actually receiving it.

Example: A teacher orders NVMe drives for a Pi 5 storage upgrade two months early after learning the supplier's lead time typically runs three to four weeks.

See also: Supply Chain Shortage

LED¶

A light emitting diode, a small electronic component that produces light when current flows through it in one direction only.

Example: A single red LED lights up when connected correctly across a GPIO pin and a current-limiting resistor.

See also: LED Polarity, Forward Voltage, NeoPixel

LED Diffuser¶

A translucent cover or material placed over an LED that spreads and softens its light, reducing harsh, pinpoint brightness and blending colors from nearby pixels.

Example: A frosted plastic LED diffuser placed over a NeoPixel strip turns individual points of light into a smooth glowing line.

LED Polarity¶

The property of an LED that requires current to flow through it in only one specific direction, from its longer positive leg to its shorter negative leg, in order to light up.

Example: If an LED's polarity is reversed on the breadboard, no current flows and the LED stays dark, but it is not damaged.

See also: LED

LED Strip¶

A flexible circuit board populated with a row of addressable LEDs, typically sold by the meter, used to create lighting effects and displays.

Example: A one-meter WS2812B LED strip is the core component of the chapter-5 NeoPixel art project, offering 60 individually addressable pixels to program.

See also: NeoPixel, Data Line

Left Motor¶

The motor that drives the wheel or wheels on the left side of a differential-drive robot, controlled independently from the right motor to enable turning.

Example: A STEM robot turns right by slowing its left motor while keeping its right motor at full speed, since the two motors are controlled independently.

See also: Right Motor, Differential Drive

Library Installation¶

The process of downloading and setting up a software package so that a program can import and use its functions.

Example: A student performs library installation by running pip install adafruit-circuitpython-neopixel so their MicroPython code can control a NeoPixel strip.

See also: Package Dependency, Package Manager

Light Dependent Resistor¶

Another common name for a photoresistor, describing a component whose resistance depends on the intensity of light striking its surface.

Example: A chapter-6 nightlight project uses a light dependent resistor, also called a photoresistor, to automatically turn on a NeoPixel strip when the room gets dark.

See also: Photoresistor

Light Painting¶

A photography and art technique that uses long-exposure camera shots to capture the trails left by moving lights, often created using programmable LED strips.

Example: Waving a NeoPixel strip running a rainbow animation in front of a long-exposure camera produces a light painting photograph.

Lighting Animation Loop¶

A repeating block of code that continuously updates a keyboard's RGB lighting pattern over time to create a moving or changing visual effect.

Example: A Pi 500+ script runs a lighting animation loop that recalculates and updates the keyboard's rainbow pattern roughly 30 times per second.

See also: Lighting Effect Script, Animation Frame

Lighting Effect Script¶

A program that defines how a keyboard's RGB lighting should change over time or in response to events, such as typing or a countdown timer.

Example: A student writes a lighting effect script for the Pi 500+ that turns every key red for one second whenever a new email notification is detected.

See also: Lighting Animation Loop, Python Keyboard Library

Lighting Preset¶

A saved, ready-to-use combination of colors and animation settings that a user can apply to a keyboard's lighting without writing custom code.

Example: A Pi 500+ keyboard tool ships with a "Focus Mode" lighting preset that a student can apply with one click instead of writing custom animation code.

See also: Lighting Effect Script

Line Following¶

A robot behavior that uses reflectance sensors to detect a colored line on the floor and continuously steers to keep the robot centered on that line.

Example: A STEM robot equipped with two infrared reflectance sensors performs line following, steering left or right to stay centered on a black tape path on the classroom floor.

See also: Reflectance Sensor, Infrared Sensor

Linux Kernel¶

The core software component of a Linux-based operating system that manages a computer's hardware, memory, and running processes.

Example: The Linux kernel running underneath Raspberry Pi OS manages which program gets to use the Pi 5's camera hardware at any given moment.

See also: Raspberry Pi OS

List Files Command¶

The Linux command, ls, used to display the names of files and folders inside the current or a specified directory.

Example: A student types ls at the terminal to run the list files command and see what Python scripts are saved in their current folder.

See also: Working Directory

Loaner Equipment Policy¶

A set of rules governing how students may temporarily borrow shared hardware, such as a Raspberry Pi 5, for use outside of scheduled class time.

Example: A school's loaner equipment policy lets a student sign out a Raspberry Pi 5 and AI HAT+ overnight to finish a capstone project at home.

See also: Classroom Kit Organization

Local Network Discovery¶

The process by which devices on the same local network find and identify one another, often used to locate a Raspberry Pi's address without knowing it in advance.

Example: A student uses local network discovery tools to find their headless Raspberry Pi's IP address on the classroom Wi-Fi before connecting over SSH.

See also: Hostname

Low Power Design¶

An approach to building hardware and software that deliberately minimizes energy consumption, extending battery life for portable and wearable projects.

Example: A wearable watch project follows low power design principles, using deep sleep and infrequent display refreshes to make a coin cell battery last for weeks.

See also: Deep Sleep, Battery Life Optimization

Machine Learning Model¶

A file containing patterns learned from data during training, which a program can use to make predictions or decisions on new, previously unseen input.

Example: The chapter-17 object-detection project loads a pretrained machine learning model file onto the AI HAT+ to recognize common household objects.

See also: Pretrained Model, Model Inference

Macro Key¶

A key, real or assigned, configured to trigger a predefined sequence of multiple actions with a single press.

Example: A student configures a spare function key on the Pi 500+ as a macro key that opens a terminal and starts their robot-control script with a single press.

See also: Custom Key Mapping

Magnetic Sensor¶

A general term for any sensor that detects the presence, strength, or direction of a magnetic field, including reed switches and Hall effect sensors.

Example: A STEM robot project uses a reed switch as a magnetic sensor to detect when it passes a magnet marking the finish line of a testing arena.

See also: Reed Switch

Make Directory Command¶

The Linux command, mkdir, used to create a new, empty folder within the file system.

Example: A student runs mkdir robot-project as the make directory command to create a fresh folder for a new capstone project's code.

Mel Frequency Cepstrum¶

A representation of a sound's short-term frequency content, adjusted to reflect how human hearing perceives pitch, commonly used as an input feature for speech and sound recognition models.

Example: The chapter-18 sound classifier converts each audio clip into a Mel-frequency cepstrum before feeding it to the model, since that representation matches how human ears perceive pitch differences.

See also: Audio Feature Extraction

Microcontroller¶

A small, self-contained chip that combines a processor, memory, and input/output pins on a single package, designed to run one program at a time to control physical devices directly.

Example: The RP2040 chip inside a Raspberry Pi Pico is a microcontroller that directly drives GPIO pins to blink an LED.

Contrast with: Single Board Computer

Microphone Array¶

A set of two or more microphones arranged together, used to capture sound with more detail than a single microphone, sometimes allowing a device to estimate the direction a sound came from.

Example: A voice-controlled robot uses a small microphone array to estimate roughly which direction a spoken "stop" command came from.

See also: Microphone Module

Microphone Module¶

A component that converts sound waves into a detailed electrical audio signal suitable for recording, analysis, or feeding into a sound-recognition program.

Example: A breadboard-mounted microphone module converts a student's voice into an audio signal that a chapter-18 sound-classification script can analyze.

See also: Sound Sensor, USB Microphone

MicroPython¶

A compact implementation of the Python programming language designed to run directly on microcontrollers, including the Raspberry Pi Pico, with limited memory and processing power.

Example: A MicroPython script just a few lines long can blink an LED on a Raspberry Pi Pico.

See also: Thonny IDE, Raspberry Pi Pico

MicroSD Storage¶

A small removable memory card commonly used to hold the operating system and files for Raspberry Pi boards that lack faster storage options.

Example: A basic Raspberry Pi 5 setup boots Raspberry Pi OS from microSD storage before a student later upgrades to a faster NVMe drive.

Contrast with: NVMe Storage

See also: SD Card Imaging

Model Accuracy¶

A measurement of how often a machine learning model's predictions match the correct answer, usually expressed as a percentage.

Example: A chapter-16 exercise reports that a sound classifier reaches 92 percent model accuracy on its validation dataset, correctly identifying most doorbell and alarm sounds.

See also: Validation Dataset, False Positive

Model Compression¶

A general set of techniques used to reduce a machine learning model's file size and computational requirements so it can run efficiently on smaller devices.

Example: Model compression techniques shrink the object-detection model enough that it fits comfortably in the Hailo accelerator's memory on the AI HAT+.

See also: Model Quantization, Edge AI

Model Inference¶

The process of running new input data through an already-trained machine learning model to produce a prediction or output.

Example: Each time the Pi 5's camera captures a frame, the object-detection script performs model inference to determine what objects are visible and where.

Contrast with: Model Training

See also: Training Versus Inference

Model Quantization¶

A technique that reduces the numeric precision used to store a machine learning model's internal values, shrinking its size and speeding up inference with a small accuracy trade-off.

Example: Model quantization converts the object-detection model's internal numbers from 32-bit to 8-bit values, shrinking the file so it runs faster on the AI HAT+ with only a small accuracy loss.

See also: Model Compression, TFLite Model Format

Model Training¶

The process of adjusting a machine learning model's internal parameters using example data so it learns to make accurate predictions.

Example: Chapter 16 walks through model training conceptually, showing how adjusting a neural network's internal weights on example images gradually improves its object-recognition accuracy.

Contrast with: Model Inference

See also: Training Versus Inference, Training Dataset

Model Zoo¶

A curated online collection of pretrained machine learning models that developers can download and use directly or adapt for their own projects.

Example: Instead of training from scratch, a chapter-17 project downloads a ready-made object-detection model from a model zoo designed for the Hailo accelerator.

See also: Pretrained Model

Momentary Switch¶

A switch that returns to its default open or closed state as soon as it is released, rather than staying in whatever position it was last set to.

Example: A tilt switch is a momentary switch that only completes its circuit while the device is tilted past a certain angle.

See also: Push Button, Tilt Switch

Motor Driver¶

An electronic circuit or chip placed between a microcontroller and a motor that supplies the higher current the motor needs while being controlled by low-current logic signals.

Example: A motor driver lets a Pico's low-power GPIO pins safely control a DC motor that needs far more current than the Pico could supply directly.

See also: H Bridge

Motor Polarity¶

The direction in which voltage is applied across a DC motor's two terminals, which determines whether the motor spins clockwise or counterclockwise.

Example: Swapping a motor's polarity through an H bridge reverses a robot wheel's spin direction, turning forward motion into reverse.

See also: DC Motor, H Bridge

Motor Speed Control¶

The use of PWM or a similar technique to vary how fast a motor spins, rather than only switching it fully on or fully off.

Example: A STEM robot uses PWM-based motor speed control to gradually slow down as it approaches a wall detected by its ultrasonic sensor, rather than stopping abruptly.

See also: PWM, DC Motor

Motor Stall¶

A condition in which a motor is powered but physically prevented from turning, causing it to draw much higher current than normal and potentially overheat.

Example: A robot wheel wedged against a wall causes a motor stall, and the code's current-monitoring safeguard shuts the motor off before it overheats.

Move File Command¶

The Linux command, mv, used to relocate a file or folder to a different location, or to rename it.

Example: A student runs mv old_test.py archive/old_test.py as the move file command to relocate an outdated script into an archive folder.

Contrast with: Copy File Command

Moving Average Filter¶

A noise-filtering technique that smooths a series of readings by continuously averaging the most recent several values instead of using each raw reading directly.

Example: A moving average filter applied to five consecutive distance readings smooths out a single noisy spike that would otherwise confuse the robot.

See also: Noise Filtering

MQTT Broker¶

A central server that receives messages published by MQTT devices and forwards them to every device subscribed to the matching topic.

Example: A Raspberry Pi 5 running Mosquitto acts as the MQTT broker in chapter 10, receiving temperature readings published by several Pico W sensor nodes.

See also: MQTT Protocol, Publish Subscribe Model

MQTT Protocol¶

A lightweight messaging protocol designed for devices with limited power and bandwidth, in which devices publish and subscribe to named topics through a central broker.

Example: A chapter-10 weather-station project uses the MQTT protocol so a battery-powered Pico W can publish sensor readings without maintaining a constant open connection.

See also: MQTT Broker, MQTT Topic, Publish Subscribe Model

MQTT Topic¶

A named channel used in the MQTT protocol to organize messages, allowing devices to publish or subscribe to only the specific categories of data they care about.

Example: A classroom of robots might each publish their battery level to an MQTT topic named classroom/robot/battery.

See also: MQTT Protocol, MQTT Broker

Multi Application Multitasking¶

An operating system's ability to run several independent programs at the same time, switching a user's attention between them without closing any.

Example: Multi application multitasking on a Raspberry Pi 500+ lets a student keep a code editor, a terminal, and a web browser all open at once.

Multi Board Communication¶

A design in which two or more separate microcontroller or computer boards exchange data with each other, often wirelessly, to coordinate a shared task.

Example: A capstone project uses multi-board communication, letting a Pico W sensor node send readings over Wi-Fi to a Raspberry Pi 5 that logs and displays them.

See also: Cross Tier Integration, Peer To Peer Communication

A machine learning approach that combines information from more than one type of input, such as both camera images and audio, to make a more reliable decision.

Example: A capstone security project uses multi-modal recognition, combining the Pi 5's camera-based person detection with its microphone's glass-break sound classification for a more reliable alert.

See also: Multi Sensor Fusion

Multi Sensor Fusion¶

The technique of combining readings from more than one sensor to make a more reliable decision than any single sensor could support on its own.

Example: Multi sensor fusion combining an ultrasonic reading and a reflectance sensor reading lets a robot distinguish a real wall from a dark patch on the floor.

See also: Sensor Driven Expression

Multimeter¶

A handheld test instrument used to measure electrical quantities such as voltage, current, and resistance in a circuit.

Example: A student uses a multimeter to confirm a breadboard's power rail is actually supplying 3.3 volts before plugging in a sensor.

See also: Continuity Test

Nano Text Editor¶

A simple, beginner-friendly text editor that runs inside a terminal, used to view and edit plain text and configuration files on Raspberry Pi OS.

Example: A student edits a configuration file directly in the terminal using the Nano text editor rather than opening a full graphical code editor.

See also: Terminal Emulator

NeoPixel¶

The trade name for a family of addressable RGB LEDs, most often WS2812B chips, that can each be individually set to a different color using a single data line.

Example: A strip of thirty NeoPixels can display a rainbow pattern where every pixel is a different color at once.

See also: WS2812B LED, Addressable LED

Neopixel Library¶

A software package that provides ready-made functions for controlling addressable LEDs, handling the precise timing the chained LED protocol requires so a programmer does not have to.

Example: Importing the neopixel library in MicroPython gives access to a fill() function that sets every pixel on a strip to the same color in one line.

See also: Show Method, Fill Method

Network Latency¶

The delay between sending data over a network and it arriving at its destination, often measured in milliseconds.

Example: High network latency between a robot and a remote control app can make the robot feel sluggish to respond to commands.

See also: Packet Loss

Network Security¶

The practices and safeguards used to protect a network and its connected devices from unauthorized access or misuse.

Example: The wireless chapter's network security section explains why a Pico W project should avoid transmitting Wi-Fi credentials in plain, unencrypted messages.

See also: Firewall Basics, Wi-Fi Credentials

Network SSID¶

The Service Set Identifier, or public name, broadcast by a Wi-Fi network that devices use to identify and select which network to join.

Example: A Pico W's setup script asks a student to enter their home Wi-Fi's network SSID, such as "MySmithFamily5G," before it can connect.

See also: Wi-Fi, Wi-Fi Credentials

Network Time Protocol¶

A standard internet protocol used to synchronize a device's clock with accurate time servers over a network connection.

Example: A headless Raspberry Pi 5 uses the Network Time Protocol to automatically set its system clock correctly the moment it connects to Wi-Fi.

See also: NTP Time Sync, Epoch Time

Neural Network¶

A machine learning model structure loosely inspired by the brain, made of layers of connected nodes that transform input data step by step to produce an output.

Example: The object-detection model running on the AI HAT+ is a neural network made of many connected layers that transform a camera frame step by step into a list of detected objects.

See also: Convolutional Neural Network, Machine Learning Model

Neural Processing Unit¶

A specialized processor designed specifically to perform the mathematical operations used in neural networks efficiently, much faster than a general-purpose CPU for that specific task.

Example: The Hailo chip on the AI HAT+ functions as a neural processing unit, running the object-detection model's math far faster than the Pi 5's CPU could alone.

See also: AI HAT Plus, Hardware Accelerator

Next Steps Learning Path¶

A suggested sequence of further topics or projects a student can pursue after completing a chapter or capstone project, based on their interests.

Example: The end of the audio-classification chapter suggests a next-steps learning path toward the capstone chapter for students interested in combining sound detection with robotics.

See also: Independent Study Extension

Noise Filtering¶

Techniques used to reduce random, unwanted fluctuations in sensor readings so the underlying real signal is easier to detect and act on.

Example: Noise filtering applied to a distance sensor's readings prevents a single stray reading from falsely triggering the robot's obstacle-avoidance behavior.

See also: Moving Average Filter

Noise Floor¶

The baseline level of background noise present in an audio recording, below which quieter, meaningful sounds cannot be reliably distinguished.

Example: A chapter-18 exercise has students measure their classroom's noise floor with a USB microphone so they can set a sound-classification threshold above typical background chatter.

See also: Signal To Noise Ratio

Non Blocking Code¶

Code written so that a time-consuming operation, such as waiting or an animation delay, does not stop the rest of the program from continuing to run. Ordinary blocking code, by contrast, pauses the entire program until that wait finishes.

Example: Non blocking code lets a robot keep checking its distance sensor even while an eye-blink animation is still playing on the display.

See also: Cooperative Multitasking

Non Maximum Suppression¶

A post-processing step in object detection that removes duplicate, overlapping bounding boxes for the same object, keeping only the single most confident detection.

Example: After detecting several overlapping boxes around the same cup, the Pi 5's object-detection pipeline applies non-maximum suppression to keep only the single highest-confidence bounding box.

See also: Bounding Box, Confidence Score

Notification Lighting Pattern¶

A predefined lighting sequence, such as a flashing color, used on a keyboard to alert a user to an event like a new message or a completed task.

Example: A Pi 500+ script uses a notification lighting pattern that flashes the Escape key orange three times whenever a background script finishes a long task.

See also: Event Driven Lighting

NTP Time Sync¶

The process of setting a device's clock to match a highly accurate time source over a network connection using the Network Time Protocol.

Example: A DS3231-equipped clock project performs an NTP time sync over Wi-Fi once a day to correct any small drift the real-time clock module has accumulated.

See also: Network Time Protocol, Real Time Clock

NVMe Storage¶

A type of solid-state storage that connects through a PCIe interface, offering much faster read and write speeds than a microSD card.

Example: Upgrading a Raspberry Pi 5 from a microSD card to NVMe storage noticeably speeds up loading the object-detection model used in the AI HAT+ chapter.

Contrast with: MicroSD Storage

See also: PCIe Interface, Storage Benchmark

Object Detection¶

A machine learning task in which a model identifies multiple objects within an image and marks the location of each one with a bounding box.

Example: Chapter 17's project performs object detection, drawing a separate bounding box and label around each cup, phone, and person visible in the camera's live feed.

Contrast with: Image Classification

See also: Bounding Box, Confidence Score

Obstacle Detection¶

The process of identifying that an object lies in a robot's path, typically by comparing a distance sensor's reading to a threshold value.

Example: A STEM robot's obstacle detection routine compares its ultrasonic sensor's reading against a 10-centimeter threshold to decide when to stop and turn.

See also: Distance Measurement, Collision Avoidance

Ohms Law¶

A fundamental electrical relationship stating that voltage equals current multiplied by resistance, used to calculate any one of these three quantities when the other two are known.

Example: A student uses Ohms Law to calculate that a 3.3-volt source through a 220-ohm resistor produces about 15 milliamps of current.

See also: Voltage, Current, Resistance

OLED Display¶

A small screen made of organic light-emitting diode pixels that each produce their own light, allowing sharp, high-contrast images without a separate backlight.

Example: An OLED display mounted on a robot's front panel draws a pair of simple cartoon eyes.

See also: SSD1306 Driver, Display Resolution

On Device Processing¶

Performing data analysis, such as sound or image recognition, directly on the local device rather than sending raw data to a remote server.

Example: Running the sound-classification model directly on the Pi 5 with its Hailo accelerator, instead of uploading audio to a website, is an example of on-device processing.

Contrast with: Cloud Versus Edge Processing

See also: Edge AI, Audio Privacy Considerations

ONNX Model Format¶

An open, standardized machine learning model file format designed to let models be shared and run across different software frameworks and hardware.

Example: A pretrained object-detection model downloaded for the AI HAT+ project is provided in the ONNX model format before being converted for the Hailo accelerator.

Contrast with: TFLite Model Format

Open Circuit¶

A break in a circuit's path that prevents current from flowing at all, often caused by a disconnected wire, a loose connection, or a burned-out component.

Example: An LED that never lights up, even with correct polarity, may indicate an open circuit from a broken jumper wire.

Contrast with: Short Circuit

Open Ended Problem¶

A challenge with no single correct solution, allowing students to explore multiple valid approaches and designs.

Example: The capstone chapter presents an open-ended problem, "build something that helps someone in your daily life," rather than specifying an exact project to replicate.

Contrast with: Constraint Based Design

Operating System Image¶

A complete, ready-to-boot copy of an operating system's files, packaged as a single file that can be written onto storage such as a microSD card or NVMe drive.

Example: A student uses the Raspberry Pi Imager to write a Raspberry Pi OS operating system image onto a microSD card before first booting their Pi 500+.

See also: SD Card Imaging, Raspberry Pi Imager

Original Invention¶

A project in which a student designs and builds a new idea of their own rather than following or modifying an existing example.

Example: For the capstone project, a student creates an original invention, a NeoPixel plant-watering reminder of their own design rather than following a project from the book.

Contrast with: Remix And Extend

Output Device¶

A component that a computer or microcontroller controls to produce a physical effect, such as light, sound, or motion, for a person to observe.

Example: A NeoPixel strip, a piezo buzzer, and an OLED display are all output devices.

Contrast with: Input Device

Overfitting¶

A problem in which a machine learning model learns the specific details and noise of its training dataset so closely that it performs poorly on new, unseen data.

Example: Chapter 16 warns that a sound classifier trained only on recordings of one student's voice may suffer from overfitting, performing poorly when a different student tries the wake-word demo.

See also: Training Dataset, Validation Dataset

Package Dependency¶

A software library or package that another program requires in order to run correctly, and which must also be installed alongside it.

Example: Installing the object-detection library on a Pi 5 automatically pulls in a package dependency for numerical computing that the detection code needs to run.

See also: Python Virtual Environment, Library Installation

Package Manager¶

A tool that automates downloading, installing, updating, and removing software on an operating system, along with any other software that package depends on.

Example: Raspberry Pi OS uses the APT package manager to install, update, and remove software such as the camera libraries needed for chapter 17's project.

See also: APT Package Manager

Packet Loss¶

The failure of some data sent over a network to arrive at its destination, which can cause missing sensor readings or dropped commands.

Example: A Pico W sensor project on a weak Wi-Fi signal experiences packet loss, causing occasional MQTT temperature readings to never reach the broker.

See also: Network Latency, Wireless Range

Pairing Process¶

The steps two Bluetooth devices follow to establish a trusted, often encrypted, connection before they can exchange data reliably.

Example: Connecting a Pico W wearable to a phone requires a Bluetooth pairing process where the two devices confirm they should trust each other before exchanging sensor data.

See also: Bluetooth Low Energy

Parallel Circuit¶

A circuit arrangement in which components are connected across the same two points, providing multiple separate paths for current so each component can operate independently.

Example: Two LEDs wired in parallel across the same power and ground rails each get the full supply voltage and can be switched independently.

Contrast with: Series Circuit

Passive Buzzer¶

A piezo buzzer that requires a program to actively generate the sound wave's frequency, typically using PWM, allowing it to play different musical notes.

Example: A passive buzzer can be programmed to play a simple melody by sending it a sequence of different PWM frequencies.

Contrast with: Active Buzzer

See also: Tone Generation

Pattern Recognition¶

The skill of noticing similarities, repeated structures, or trends across problems or data so that a known solution or shortcut can be reused.

Example: After wiring three different LED circuits, a student notices every one needs a current-limiting resistor and applies that pattern automatically to the next circuit.

PCIe Interface¶

Peripheral Component Interconnect Express, a high-speed connection standard used on the Raspberry Pi 5 to attach fast external devices such as NVMe storage.

Example: The Raspberry Pi 5's PCIe interface lets a student attach an NVMe SSD for much faster storage than a microSD card offers.

See also: NVMe Storage

PCM5102 DAC¶

A specific digital-to-analog converter chip commonly used to convert a digital audio signal into an analog signal that can drive a speaker or headphones.

Example: A chapter-18 audio project wires a PCM5102 DAC to a Pico's I2S pins to convert digital audio data into an analog signal a speaker can play.

See also: I2S Audio Interface, Speaker Output

Peer Code Review¶

A practice in which a student examines a classmate's code to check for errors, suggest improvements, and share knowledge.

Example: Before submitting their capstone project, students exchange laptops for a peer code review, checking each other's Python scripts for bugs and unclear variable names.

See also: User Testing

Peer To Peer Communication¶

A network communication pattern in which devices exchange data directly with one another rather than routing every message through a central server.

Example: Two Pico W boards exchange sensor readings directly over Wi-Fi in a peer-to-peer communication demo, without routing messages through an MQTT broker.

See also: Swarm Robotics

Per Key RGB Lighting¶

A keyboard feature in which each individual key has its own independently controllable RGB LED, allowing every key to display a different color at the same time.

Example: Per key RGB lighting on the Raspberry Pi 500+ lets a Python script turn the W, A, S, and D keys green while every other key stays off.

See also: RGB LED Zone, Keyboard Matrix

Photoresistor¶

A component whose electrical resistance changes based on the amount of light falling on it, typically decreasing in resistance as light increases.

Example: A photoresistor placed in a voltage divider lets a Pico detect whether a room's lights have been turned off.

See also: Light Dependent Resistor, Voltage Divider

Physical Computing¶

The practice of building interactive systems that sense and respond to the physical world using sensors, actuators, and a programmable computer or microcontroller.

Physical computing is the unifying theme of this book, connecting code running on a Pico or Raspberry Pi to real-world lights, motors, sounds, and sensors.

Example: A NeoPixel that changes color when a photoresistor detects darkness is a small physical computing system.

See also: Sensor, Actuator, Microcontroller

Piezo Buzzer¶

A small component that produces sound by vibrating a piezoelectric material when an electrical signal is applied to it.

Example: A STEM robot's piezo buzzer beeps twice whenever its distance sensor detects an obstacle closer than 10 centimeters.

See also: Active Buzzer, Passive Buzzer

40 Pin Header¶

The specific 40-pin GPIO header layout standard across most Raspberry Pi single board computers, ensuring compatibility with a wide range of add-on boards.

Example: The same 40-pin header layout on both the Raspberry Pi 500+ and Raspberry Pi 5 means a NeoPixel add-on board built for one also fits the other.

See also: GPIO Header

Pin Numbering¶

The labeling scheme used to identify each physical pin on a microcontroller or GPIO header, allowing code to refer to a specific pin unambiguously.

Example: MicroPython code refers to Pin(25) to control the onboard LED because pin numbering identifies GPIO 25 as that LED's connection.

See also: GPIO Pin

Pixel Buffer¶

An area of memory that holds the color or on-off value for every pixel of a display before it is sent to the screen to be shown.

Example: A program draws a circle into the pixel buffer, then sends the whole buffer to the OLED display at once.

See also: Frame Buffer, Display Resolution

Pixel Index¶

A number identifying the position of a single LED within an addressable strip, counted starting from the end connected to the data source.

Example: Pixel index 0 refers to the first NeoPixel in a strip, closest to the microcontroller's data pin.

See also: Set Pixel Color

Polling¶

A technique in which a program repeatedly checks the state of an input, such as a sensor or button, at regular intervals to see if it has changed.

Example: A robot's main loop polls its ultrasonic sensor every 50 milliseconds to check whether an obstacle has come into range.

Contrast with: Interrupt

Pomodoro Timer Lighting¶

A keyboard lighting effect that visually counts down a focused work interval, based on the Pomodoro time-management technique, often by progressively dimming or changing key colors.

Example: A Pi 500+ productivity script uses Pomodoro timer lighting, gradually dimming the number-row keys from green to red over a 25-minute focus session.

See also: Timer Feature

Portfolio Artifact¶

A single piece of evidence, such as a photo, code file, or write-up, saved into a student portfolio to document a specific accomplishment.

Example: A photo of a finished NeoPixel art piece, saved alongside its source code, becomes a portfolio artifact a student includes in their end-of-year student portfolio.

See also: Student Portfolio

Potentiometer¶

A variable resistor with a rotating knob or sliding control that lets a user manually adjust resistance, often used to produce a variable voltage for analog input.

Example: A potentiometer wired to an analog pin lets a student manually control the brightness of an LED by turning a knob.

See also: Voltage Divider

Power Budget For LEDs¶

A calculation of the total current an LED strip or project may draw at full brightness, used to size a power supply or battery correctly and avoid overloading it.

Example: A power budget for LEDs calculation shows that sixty NeoPixels at full white brightness could draw more current than a small USB power bank can safely supply.

See also: Current Draw Per LED

Power Rail¶

A dedicated strip on a breadboard, or a dedicated conductor on a board, used to distribute a single voltage level, such as power or ground, to multiple components.

Example: A breadboard project connects a Pico's 3.3V and ground pins to the breadboard's red and blue power rails so multiple LEDs can share the same power source.

See also: Breadboard Rail

Power Supply Rating¶

The maximum voltage and current a power supply is designed to safely deliver, which must meet or exceed a device's actual power requirements.

Example: A Raspberry Pi 5 requires a USB-C power supply with a rating of at least 5V/5A to run reliably with the AI HAT+ attached.

See also: USB C Power Delivery

Power Switch¶

A switch that connects or disconnects a device's battery from the rest of its circuit, allowing the device to be turned fully on or off.

Example: A STEM robot kit includes an inline power switch between the battery pack and the Pico so students can turn the robot off without unplugging wires.

See also: Battery Pack

Presentation Skills¶

The ability to clearly explain a project's purpose, design, and results to an audience through speaking and visual aids.

Example: The capstone chapter's rubric scores presentation skills separately from code quality, evaluating how clearly a student explains their NeoPixel project during Demo Day.

See also: Project Demo Day

Pretrained Model¶

A machine learning model that has already been trained on a large dataset by someone else and can be used directly, or adapted, without training it from scratch.

Example: Instead of training from scratch, the chapter-17 object-detection project loads a pretrained model already capable of recognizing common household objects.

See also: Machine Learning Model, Model Zoo

Price Tier¶

A grouping of Raspberry Pi products and kits by approximate cost, used in this book to help teachers and families match a project's ambition to their budget.

Example: This book organizes projects into price tiers ranging from a fifteen-dollar Pico breadboard kit up to a Raspberry Pi 5 with an AI HAT+.

See also: Total Cost Of Ownership

Priority Based Behavior¶

A robot control approach in which several possible behaviors are ranked by importance, and the robot always executes the highest-ranked behavior whose trigger conditions are currently met.

Example: In priority based behavior, an obstacle-avoidance response always overrides a lower-priority line-following behavior when both conditions are true at once.

See also: Behavior Tree

Process Management¶

The set of tools and techniques used to view, control, and stop currently running programs on an operating system.

Example: A student uses process management tools in the terminal to find and stop a Python script that is still running in the background after they closed its window.

See also: Task Manager

Product Decision Framework¶

A structured set of questions and criteria, such as budget, required peripherals, and learning goals, used to choose which Raspberry Pi product best fits a project or classroom.

Example: A teacher uses a product decision framework to decide that a Pico W, not a full Raspberry Pi 5, is the right choice for a wireless weather-alert project.

See also: Price Tier

Project Budgeting¶

The process of estimating and tracking the total cost of components, tools, and supplies needed to complete a specific project.

Example: A teacher does project budgeting for a classroom NeoPixel unit, estimating $12 per Pico, $8 per LED strip, and $5 for a breadboard across 25 students.

See also: Bill Of Materials, Classroom Budget

Project Demo Day¶

A scheduled event where students present their finished projects to classmates, teachers, or a wider audience.

Example: At the end of the STEM robot chapter, the class holds a Project Demo Day where each team drives their robot through the testing arena for classmates.

See also: Presentation Skills, Robot Day Showcase Format

Project Planning Document¶

A written record, created before building begins, that outlines a project's goals, required parts, timeline, and division of tasks.

Example: Before wiring anything, a capstone team fills out a project planning document listing required parts, a two-week timeline, and who is responsible for the code versus the enclosure.

See also: Design Brief, Engineering Design Process

Project Reflection¶

A written or spoken review, completed after finishing a project, in which a student considers what worked, what did not, and what they learned.

Example: After finishing their wearable watch, a student writes a project reflection describing how soldering the DS3231 module was harder than expected but the round display was worth it.

See also: Course Wrap Up Reflection

Prototype¶

An early, working version of a project built to test an idea, uncover problems, and gather feedback before creating a final version.

Example: Before soldering a permanent enclosure, a maker builds a breadboard prototype of a clock circuit to confirm the wiring works.

See also: Iterative Design

Prototype Iteration¶

A single round of building, testing, and revising a prototype as part of an iterative design process.

Example: A capstone team's first prototype iteration of their alert light used a single NeoPixel; after testing, a second iteration switched to a full strip for better visibility.

See also: Iterative Design, Prototype

Pseudocode¶

An informal, plain-language description of a program's logic that follows the structure of code without requiring exact syntax from a specific programming language.

Example: "If the button is pressed, turn on the LED" is pseudocode a student writes before translating it into MicroPython.

See also: Algorithm, Flowchart

A messaging pattern in which senders, called publishers, post messages to named topics without knowing who will receive them, and receivers, called subscribers, choose which topics to listen to.

Example: Chapter 10's weather-station project follows the publish-subscribe model, where a Pico W publishes temperature readings to an MQTT topic without knowing which devices are subscribed to read them.

See also: MQTT Protocol, MQTT Topic

Pull Down Resistor¶

A resistor connected between an input pin and ground that holds the pin at a low, or "off," reading whenever nothing else is actively pulling it high.

Example: A button wired with a pull down resistor reads low normally and rises to high the instant the button connects the pin to the voltage rail.

Contrast with: Pull Up Resistor

Pull Up Resistor¶

A resistor connected between an input pin and the positive voltage rail that holds the pin at a high, or "on," reading whenever nothing else is actively pulling it low.

Example: A button wired with a pull up resistor reads high normally and drops to low the instant the button connects the pin to ground.

Contrast with: Pull Down Resistor

Push Button¶

A simple mechanical switch that closes an electrical connection only while it is being physically pressed, then reopens the connection when released.

Example: A push button wired to a Pico's GPIO pin lets a student manually trigger a NeoPixel animation.

Contrast with: Momentary Switch is the general category; a push button is the everyday tactile version of it.

PWM¶

Pulse Width Modulation, a technique that rapidly switches a digital pin on and off to simulate a variable voltage level, used to control brightness, speed, or tone.

Example: PWM applied to a DC motor's control pin lets a robot smoothly vary its speed instead of only turning fully on or off.

See also: Duty Cycle, Motor Speed Control

Python Keyboard Library¶

A software package that provides Python functions for reading keyboard events and controlling per-key RGB lighting on supported keyboards such as the Raspberry Pi 500+.

Example: A student imports a Python keyboard library on their Pi 500+ to detect key presses and light up individual RGB zones from a script.

See also: Keyboard API, Lighting Effect Script

Python Virtual Environment¶

An isolated Python installation created for a specific project, keeping its installed packages separate from the system's main Python installation and from other projects.

Example: Before installing the object-detection libraries, a student creates a Python virtual environment on their Pi 5 so those packages don't conflict with ones used by other projects.

See also: Package Dependency, Library Installation

Rainbow Cycle¶

A NeoPixel animation that continuously shifts the hue displayed across a strip, producing a moving rainbow of color.

Example: The chapter-5 NeoPixel project's signature effect is a rainbow cycle that continuously shifts hue across the LED strip, producing a smooth moving rainbow.

See also: Color Wheel, Animation Frame

RAM Shortage¶

A condition in which a device does not have enough random-access memory to run a program, load a model, or keep multiple applications open at once, causing slowdowns or crashes.

Example: Running a large AI model on a Raspberry Pi board with too little RAM can cause the program to freeze or be shut down by the operating system.

Raspberry Pi 5¶

A full-featured single-board computer built around the Broadcom BCM2712 chip, used in this book's advanced projects involving cameras, the AI HAT+, and real-time image and sound recognition.

Example: A Raspberry Pi 5 paired with a camera module and the AI HAT+ identifies objects in a live video feed.

See also: Broadcom BCM2712, AI HAT Plus

Raspberry Pi 500+¶

A keyboard-shaped single-board computer that runs a full Linux desktop and includes individually addressable RGB lighting under every key, used in this book for both general computing lessons and per-key lighting projects.

Example: Students write a Python script on the Pi 500+ that turns each key a different color as it is pressed.

See also: Per Key RGB Lighting, Raspberry Pi OS

Raspberry Pi Foundation¶

The UK-based charity that designs the Raspberry Pi family of computers and funds educational programs to make computing and digital making accessible to everyone.

Example: The Raspberry Pi Foundation publishes free lesson plans and maintains the MicroPython firmware used throughout this book's Pico projects.

Raspberry Pi Imager¶

An official software tool used to download an operating system and write it onto an SD card or other storage device, preparing it to boot a Raspberry Pi.

Example: A student uses Raspberry Pi Imager on a laptop to download Raspberry Pi OS and write it onto a microSD card for their new Pi 500+.

See also: SD Card Imaging

Raspberry Pi OS¶

The official Linux-based operating system developed for Raspberry Pi computers, providing a desktop environment, pre-installed software, and command-line tools.

Example: The Linux desktop chapter has students navigate Raspberry Pi OS's file manager, terminal, and settings menu on their Pi 500+ for the first time.

See also: Linux Kernel, Desktop Environment

Raspberry Pi Pico¶

A low-cost microcontroller board built around the RP2040 chip, designed for breadboard prototyping and programmable in MicroPython or C, without its own display or operating system.

Example: A Raspberry Pi Pico mounted on a breadboard controls a single blinking LED in this book's first hands-on project.

See also: RP2040 Chip, Microcontroller

Raspberry Pi Pico 2¶

A newer microcontroller board built around the faster RP2350 chip, offering more memory and processing power than the original Pico while keeping the same board layout.

Example: A Pico 2 runs a more demanding sensor-fusion robot program that would run slowly on an original Pico.

See also: RP2350 Chip

Raspberry Pi Pico W¶

A version of the Raspberry Pi Pico that adds built-in Wi-Fi and Bluetooth Low Energy hardware, allowing projects to connect to networks and communicate wirelessly.

Example: A Pico W checks an online weather service and lights a NeoPixel blue when rain is forecast.

See also: CYW43 Chip, Wi-Fi

Reactive Lighting¶

A keyboard lighting style in which colors change immediately in response to specific key events, such as lighting a key the instant it is pressed.

Example: A Pi 500+ typing game uses reactive lighting, turning each key green the instant it is correctly pressed rather than following a preset animation.

Contrast with: Ambient Lighting Mode

See also: Key Press Event, Event Driven Lighting

README File¶

A text file, typically named README, placed alongside a project's code to explain what the project does and how to set it up and run it.

Example: A capstone team writes a README file alongside their GitHub repository explaining how to wire their NeoPixel alert device and run its Python script.

See also: Technical Documentation, GitHub Repository

Real Time Clock¶

A dedicated chip that keeps track of the current time and date continuously, even while the rest of a device is powered off, usually backed by its own small battery.

Example: A real time clock keeps accurate time on a wearable watch project even after it is unplugged from USB power overnight.

See also: DS3231 Module, Coin Cell Battery

Real Time I O¶

Input and output operations that must be handled within a strict, predictable time window, a requirement some sensor and control applications demand of a Raspberry Pi's GPIO pins.

Example: A line-following STEM robot depends on real-time I/O, reading its infrared sensors and adjusting motor speed within milliseconds to stay on the tape path.

See also: GPIO Pin

Real Time Video Pipeline¶

The chain of steps, from capturing a camera frame through running inference and displaying results, that must complete quickly enough to keep up with a live video feed.

Example: The chapter-17 project's real-time video pipeline captures, processes, and displays object-detection results fast enough to keep up with a live camera feed without visible lag.

See also: Video Stream, Camera To Model Pipeline

Rechargeable Battery¶

A battery designed to be recharged and reused many times after its stored energy is depleted, rather than being discarded after a single use.

Example: A robot kit's rechargeable battery pack is plugged into a charger overnight instead of being replaced with fresh disposable batteries.

See also: Battery Pack, Battery Life Optimization

Reed Switch¶

A switch that closes or opens its contacts in response to a nearby magnetic field, commonly used to detect whether a door, lid, or nearby magnet is present.

Example: A reed switch mounted near a robot's chassis can detect when the robot passes close to a magnetic marker on the floor.

See also: Magnetic Sensor

Reflectance Sensor¶

A sensor that shines light, usually infrared, onto a surface and measures how much bounces back, allowing it to distinguish light surfaces from dark ones such as a line on the floor.

Example: A reflectance sensor reads a strong return signal over white floor tile and a weak return signal over a black line.

See also: Line Following, Infrared Sensor

Region Of Interest¶

A specific, limited portion of an image selected for closer analysis, used to focus processing on only the part of the frame that matters.

Example: A Pi 5 project narrows its object-detection search to a region of interest in the center of the frame to ignore motion near the camera's edges.

See also: Image Preprocessing

Remix And Extend¶

An approach to project work in which a student starts from an existing project example and modifies or adds to it to create something new.

Example: A student uses a remix-and-extend approach, starting from the book's basic rainbow-cycle NeoPixel example and adding a photoresistor so the animation only runs after dark.

Contrast with: Original Invention

See also: Companion Book Cross Reference

Remote Control Interface¶

A user-facing control, such as a webpage or app screen, that lets a person send commands to a device over a wireless connection.

Example: A Pico W-based robot exposes a simple webpage as its remote control interface, letting a student tap on-screen arrow buttons to drive it from a phone.

See also: Web Server, REST Endpoint

The act of accessing and controlling a computer's operating system from a different device over a network, rather than sitting directly in front of it.

Example: A student performs remote login over SSH to control their headless Raspberry Pi 5 from a laptop in another room.

See also: SSH Protocol, Headless Setup

Remove File Command¶

The Linux command, rm, used to permanently delete a file or, with an additional option, an entire folder.

Example: A student runs rm old_notes.txt as the remove file command to permanently delete a leftover text file from their project folder.

Requirements Gathering¶

The process of identifying and documenting exactly what a project must accomplish before design or construction begins.

Example: Before starting the capstone project, a team does requirements gathering, listing that their device must run on battery power and respond to sound within one second.

See also: Design Brief, Engineering Design Process

Resistance¶

A material's opposition to the flow of electric current, measured in ohms, which limits how much current flows for a given voltage.

Example: A 220-ohm resistor placed in series with an LED limits the current so the LED does not burn out.

See also: Ohms Law, Resistor

Resistor¶

An electronic component manufactured to provide a specific, fixed amount of resistance in a circuit, used to limit current or divide voltage.

Example: A resistor placed between a GPIO pin and an LED protects the LED from excess current.

See also: Resistance, Current Limiting Resistor

REST Endpoint¶

A specific network address on a web server that responds to requests for a particular resource or action, following a common, predictable web design style.

Example: A REST endpoint at /led/on on a Pico W's web server turns on an LED whenever it receives a request.

See also: Web Server, JSON Data Format

Reusable Versus Consumable¶

A distinction made in project planning between components that can be used again in future projects, called reusable, and parts that are used up or destroyed during a single project, called consumable.

Example: A Raspberry Pi Pico is reusable across many projects, while a coin cell battery is consumable and must eventually be replaced.

RGB Color Model¶

A method of representing color as a combination of three values for red, green, and blue light intensity, which combine to produce a wide range of visible colors.

Example: Setting a NeoPixel's RGB color model values to (255, 0, 0) produces pure red.

See also: RGB Value, Color Mixing

RGB LED Zone¶

An individually addressable lighting region on a keyboard, often corresponding to a single key, that can be set to its own color independent of other zones.

Example: Each key on the Pi 500+ keyboard corresponds to its own RGB LED zone, letting a student set the W, A, S, and D keys to four different colors independently.

See also: Per Key RGB Lighting

RGB Value¶

A specific triplet of numbers, typically ranging from 0 to 255 each, that defines the red, green, and blue intensity used to set an LED's color.

Example: The RGB value (0, 255, 0) sets a NeoPixel to full green with no red or blue mixed in.

See also: RGB Color Model

Right Motor¶

The motor that drives the wheel or wheels on the right side of a differential-drive robot, controlled independently from the left motor to enable turning.

Example: A STEM robot spins in place by driving its left motor forward and its right motor backward at the same speed.

See also: Left Motor, Differential Drive

Robot Behavior Loop¶

The main repeating program structure in a robot's code that continuously reads sensors, evaluates the current state, and issues motor commands.

Example: The chapter-7 STEM robot's main program is a robot behavior loop that repeatedly reads the ultrasonic sensor, checks the current state, and sends new motor commands.

See also: Sense Think Act Cycle, State Based Behavior

Robot Calibration¶

The process of adjusting a robot's sensor thresholds, motor speeds, or timing values so its behavior matches the specific physical robot and environment it operates in.

Example: Before a demo, a team performs robot calibration, adjusting their line-following robot's sensor threshold values because their classroom floor is lighter than the one used when the code was written.

See also: Calibration

Robot Chassis¶

The structural frame or body of a robot that holds the motors, wheels, battery, and electronics together in a fixed arrangement.

Example: The plastic robot chassis in the nineteen-dollar STEM robot kit has pre-drilled mounting holes for two DC motors.

See also: Chassis Assembly

Robot Day Showcase Format¶

An event format in which students demonstrate their robots completing tasks, such as navigating a testing arena, in front of an audience.

Example: The chapter-7 robot unit ends with a Robot Day showcase format, where each team demonstrates their robot navigating a taped testing arena in front of the class.

See also: Robot Testing Arena, Project Demo Day

Robot Personality¶

The consistent combination of behaviors, expressions, and sounds designed into a robot to make it feel like it has a distinct character.

Example: An OLED-equipped robot's robot personality combines a curious blinking idle animation, a rising buzzer tone, and quick head-turning motion whenever it detects something new.

See also: Behavior Tree, Facial Expression Design

Robot Safety Stop¶

A built-in behavior or manual control that immediately halts a robot's motors to prevent injury or damage during testing.

Example: A STEM robot's code checks for a raised hand over its distance sensor as a robot safety stop, immediately halting both motors during testing.

See also: Emergency Stop Button

Robot Testing Arena¶

A designated physical space, often marked with tape lines or small obstacles, used to test and demonstrate a robot's navigation and sensing behaviors.

Example: A classroom sets up a robot testing arena using painter's tape on the floor to mark a line-following path and a few cardboard-box obstacles.

See also: Robot Day Showcase Format

Rolling Shutter Camera¶

A camera design that captures an image by scanning across rows of pixels in sequence rather than all at once, which can cause distortion when photographing fast-moving objects.

Example: The standard Camera Module used in most chapter-17 projects is a rolling shutter camera, which can show slight skew when photographing a fast-spinning robot wheel.

Contrast with: Global Shutter Camera

See also: Image Sensor

Root Cause Analysis¶

A structured process of tracing a problem's visible symptoms back to the single underlying condition that actually caused it, rather than only fixing the symptom.

Example: A flickering LED strip's root cause turns out to be a loose ground wire, not a software bug, after the student traces the symptom back through the circuit.

See also: Debugging

Root User¶

The special administrative account on a Linux system that has unrestricted permission to read, modify, or delete any file or setting.

Example: A student runs sudo raspi-config on their Pi 500+, briefly acting as the root user to change a system-wide setting that a regular account can't modify.

See also: Sudo Command, File Permissions

Round Display¶

A circular screen, often used in wearable watch and clock projects to resemble the face of a traditional analog or digital wristwatch.

Example: The chapter-9 wristwatch project uses a round display driven by a GC9A01 chip to resemble the face of a traditional analog watch.

See also: GC9A01 Driver, Watch Face Design

RP2040 Chip¶

The dual-core microcontroller chip designed by the Raspberry Pi Foundation that powers the original Raspberry Pi Pico and Pico W boards.

Example: MicroPython code running on the RP2040 chip reads a photoresistor's voltage and adjusts an LED's brightness in response.

See also: Raspberry Pi Pico

RP2350 Chip¶

A more powerful microcontroller chip designed by the Raspberry Pi Foundation, used in the Raspberry Pi Pico 2, offering more memory and processing headroom than the RP2040.

Example: A Raspberry Pi Pico 2 built around the RP2350 chip gives a chapter-17 style project more processing headroom than the original Pico's RP2040 for tasks like driving a busy NeoPixel animation and reading several sensors at once.

See also: Raspberry Pi Pico 2

Rubber Duck Debugging¶

A debugging technique in which a programmer explains their code line by line, out loud, to an object or listener, often revealing the source of an error in the process of explaining it.

Example: A student stuck on a motor-control bug explains each line of code to a classmate and realizes partway through that the left and right motor pins were swapped.

See also: Debugging

Safety Guidelines¶

A set of rules and best practices established to reduce the risk of injury or equipment damage while working with electronics and tools.

Example: Chapter 3's safety guidelines remind students to disconnect a breadboard's power source before rewiring any components.

See also: Electrical Safety, Battery Safety

Sampling Rate¶

The number of times per second a sensor's value is measured and recorded, which determines how finely changes over time can be detected.

Example: Increasing a microphone's sampling rate captures higher-pitched sounds accurately, while a low sampling rate can miss rapid changes entirely.

See also: Audio Sampling Rate

Saturation¶

The attribute of a color describing its intensity or purity, ranging from a vivid, fully saturated color to a washed-out, grayish version of the same hue.

Example: Lowering an LED's saturation while keeping its hue at red shifts the color from a vivid red toward a pale pink.

See also: Hue, Brightness

Schematic Diagram¶

A standardized diagram that represents a circuit using symbols for components and lines for connections, showing the circuit's logical structure rather than its physical layout.

Example: A schematic diagram of an LED circuit shows a resistor symbol and an LED symbol connected by lines, without showing exactly where they sit on a breadboard.

Contrast with: Circuit Diagram

Science Fair Format¶

A structured presentation style, often including a labeled display board and a project summary, traditionally used to share science and engineering projects with judges or visitors.

Example: A student adapts their capstone project into science fair format, adding a labeled tri-fold display board explaining the NeoPixel sensor project's design and results.

See also: Project Demo Day

Screen Saver Mode¶

A display behavior that turns off or dims the screen, or shows a moving pattern, after a period of inactivity to reduce power use or prevent pixel wear.

Example: A digital clock project switches its OLED display into screen saver mode after five minutes of no button presses, dimming the screen to reduce power use.

See also: Sleep Mode

SD Card Imaging¶

The process of writing a complete operating system, including all its files and settings, onto an SD card so a Raspberry Pi can boot from it.

Example: Before class, a teacher performs SD card imaging on twenty microSD cards at once, writing the same Raspberry Pi OS setup onto each for a classroom set of Pi 500+ units.

See also: Raspberry Pi Imager, MicroSD Storage

Sense Think Act Cycle¶

A repeating pattern used to design physical computing programs in which a device first reads sensor data, then decides what to do with that data, and finally commands an actuator.

Example: A STEM robot senses distance with its ultrasonic sensor, thinks by comparing the reading to a stop threshold, and acts by braking or turning its motors.

See also: Feedback Loop, State Based Behavior

Sensor¶

A component that measures a physical quantity, such as light, distance, temperature, or sound, and converts it into an electrical signal a microcontroller can read.

Example: An ultrasonic sensor measures the distance to the nearest wall so a robot can avoid a collision.

See also: Input Device, Actuator

Sensor Driven Expression¶

A design approach in which a robot's facial expression or lighting changes automatically based on live sensor readings, such as switching to a surprised face when an obstacle appears suddenly.

Example: An OLED robot's sensor-driven expression switches its face to "surprised" the instant its ultrasonic sensor detects an object suddenly appearing less than 5 centimeters away.

See also: Multi Sensor Fusion, Emotion State

Sensor Reading Loop¶

A repeating block of code that periodically checks one or more sensors and reacts to their current values, forming the core of most physical computing programs.

Example: Nearly every project from the photoresistor nightlight to the STEM robot centers on a sensor reading loop that checks a sensor's value every few milliseconds and reacts accordingly.

See also: Polling, Sense Think Act Cycle

Sensor To Cloud Pipeline¶

A data flow in which a sensor's readings are captured by a microcontroller, transmitted over a network, and stored or processed by a remote service.

Example: A weather-station capstone project forms a sensor-to-cloud pipeline, with a Pico W's temperature readings traveling over MQTT to a Raspberry Pi 5 that logs them to a file.

See also: Cross Tier Integration, MQTT Protocol

Series Circuit¶

A circuit arrangement in which components are connected end to end along a single path, so the same current flows through every component in turn.

Example: A resistor and an LED wired in series share the same current, since there is only one path for it to follow.

Contrast with: Parallel Circuit

Set Pixel Color¶

An operation that assigns a specific color value to one individual pixel within an addressable LED strip, identified by its pixel index.

Example: Using set pixel color to change only pixel index 3 to red leaves every other pixel on the strip unchanged.

Contrast with: Fill Method

Seven Segment Display¶

A display made of seven individually controllable line-shaped segments arranged to form any digit from zero through nine.

Example: A four-digit seven segment display shows a clock's hours and minutes as glowing red numerals.

See also: TM1637 Driver

Shared Component Bin¶

A container of commonly used parts, such as resistors or jumper wires, kept available for any student or group to draw from rather than being assigned to one kit.

Example: A classroom keeps a shared component bin of extra resistors and jumper wires that any student can draw from if their kit is missing one.

See also: Storage And Inventory

Shell¶

A program that reads commands typed by a user, interprets them, and carries out the requested action, forming the core of a command line interface.

Example: The Bash shell on a Pi 500+ reads a typed ls command, interprets it, and lists the files in the current folder.

See also: Bash Shell, Command Line Interface

Shell Prompt¶

The text displayed by a shell, often ending in a dollar sign, that indicates the system is ready to accept a new typed command.

Example: After opening a terminal, a student sees a shell prompt ending in $ on their Pi 500+, showing the system is ready for a new command.

See also: Bash Shell

Shell Script¶

A text file containing a sequence of shell commands that can be run together as a single program.

Example: A student writes a shell script named startup.sh that runs their robot's Python program automatically each time the Pi boots.

See also: Bash Shell, Cron Job

Shift Register¶

A chip that converts data sent one bit at a time into multiple parallel output signals, allowing a microcontroller to control many outputs using only a few pins.

Example: A shift register lets a Pico control eight separate LEDs using only three GPIO pins instead of eight.

See also: 74HC595 Chip

Short Circuit¶

An unintended low-resistance connection between two points in a circuit, often between power and ground, that allows a surge of current to flow and can damage components.

Example: Two stray wire strands touching on a breadboard created a short circuit that immediately drained the battery pack.

Contrast with: Open Circuit

Show Method¶

A function provided by an LED control library that sends the current pixel color data out to the physical LED strip, making any previously set colors actually appear.

Example: Calling the show method after setting several pixel colors is what actually makes those colors visible on the strip.

See also: Neopixel Library

Signal To Noise Ratio¶

A measurement comparing the strength of a desired audio signal to the strength of unwanted background noise, usually expressed in decibels.

Example: A microphone placed too close to a robot's motor picks up a low signal to noise ratio, making the spoken commands hard for the model to recognize.

See also: Noise Floor

Single Board Computer¶

A complete computer, including processor, memory, storage interface, and input/output ports, built on one circuit board and capable of running a full operating system.

Example: The Raspberry Pi 5 is a single board computer that boots Raspberry Pi OS and can run a web browser, unlike the Pico microcontroller.

Contrast with: Microcontroller

Sleep Mode¶

A reduced-power state in which a microcontroller pauses most processing but can wake quickly in response to a timer or external event.

Example: A wearable watch project uses sleep mode between screen refreshes so the Pico wakes quickly when a button is pressed but conserves battery the rest of the time.

Contrast with: Deep Sleep

See also: Battery Life Optimization

Socket Programming¶

Writing code that opens a network connection endpoint, called a socket, to send and receive data directly between two devices over a network.

Example: An advanced capstone project uses socket programming to open a direct network connection between a Raspberry Pi 5 and a laptop for streaming sensor data.

See also: HTTP Protocol

Software Update¶

The process of installing a newer version of an operating system or application to fix bugs, patch security issues, or add features.

Example: A student runs sudo apt update && sudo apt upgrade to perform a software update on their Pi 500+ before starting the AI HAT+ chapter's projects.

See also: Update System Command

Sound Classification¶

A machine learning task in which a model assigns a category label, such as "dog bark" or "doorbell," to a short clip of audio.

Example: Chapter 18's project performs sound classification, labeling a captured audio clip as "doorbell," "dog bark," or "background noise."

See also: Sound Event Detection, Environmental Sound Class

Sound Event Detection¶

A machine learning task that identifies not just what kind of sound occurred but also when it started and ended within a longer audio recording.

Example: Beyond simple sound classification, a chapter-18 extension performs sound event detection, marking the exact moment a smoke alarm started and stopped within a longer recording.

See also: Sound Classification

Sound Feedback¶

The use of tones, beeps, or melodies played through a buzzer or speaker to signal a robot's current state or a specific event to the user.

Example: A STEM robot uses sound feedback, playing a rising two-note buzzer melody whenever it successfully completes the testing arena's obstacle course.

See also: Buzzer Melody, Piezo Buzzer

Sound Sensor¶

A module that detects the presence or loudness of nearby sound and converts it into an electrical signal, often used to trigger a simple on-off response.

Example: A sound sensor set to trigger on loud claps can start a robot moving.

Contrast with: Microphone Module, which typically provides a detailed waveform rather than a simple loud-or-quiet signal.

Sparkle Animation¶

A lighting pattern in which randomly chosen pixels briefly light up and fade, creating a twinkling effect across a strip.

Example: A NeoPixel art project runs a sparkle animation where random pixels along the strip briefly flash white and fade, like twinkling stars.

Contrast with: Chase Animation

Speaker Output¶

The analog audio signal produced by an amplifier or DAC that physically drives a speaker to produce sound.

Example: After passing through a PCM5102 DAC, the analog speaker output drives a small speaker to play the alert tone chosen in the chapter-18 sound project.

See also: PCM5102 DAC, Amplifier Module

Spectrogram¶

A visual representation of sound that plots frequency against time, with color or brightness indicating the strength of each frequency at each moment.

Example: A spectrogram of a spoken word shows dark bands shifting position over time as different vowel and consonant sounds are produced.

See also: Frequency Spectrum

Speech To Text¶

A technology that converts spoken audio into written text.

Example: A voice-command robot project could add speech-to-text so a student's full spoken sentence, not just a single keyword, gets converted into readable commands.

Contrast with: Text To Speech

See also: Voice Command

SPI Protocol¶

A four-wire communication standard that allows fast data transfer between a microcontroller and a peripheral device, using separate lines for clock, data in, data out, and device selection.

Example: A TFT display uses the SPI protocol to refresh its screen much faster than an I2C-connected OLED could manage.

Contrast with: I2C Protocol

SSD1306 Driver¶

A common controller chip used in small monochrome OLED display modules that translates commands and pixel data from a microcontroller into the signals needed to light the display.

Example: The OLED expressive-robot chapter relies on the SSD1306 driver chip to translate a Pico's pixel data into the signals that light up the small monochrome display.

See also: OLED Display, I2C Protocol

SSH Protocol¶

Secure Shell, a network protocol that allows a user to securely log into and control a computer's command line from another device over a network.

Example: A student connects to a headless Raspberry Pi 5 from their laptop using the SSH protocol to run commands without a monitor attached.

See also: Remote Login

State Based Behavior¶

A robot control approach in which the robot's actions depend on which named state it currently occupies, with sensor events causing transitions between states.

Example: In state based behavior, a robot in the "line following" state switches to the "obstacle avoiding" state as soon as its distance sensor detects a wall.

See also: State Machine, Robot Behavior Loop

State Machine¶

A model of a system's behavior made up of a fixed set of named conditions, called states, along with rules describing which events cause the system to move from one state to another.

Example: A robot's state machine might include "idle," "moving forward," and "avoiding obstacle" states, switching between them based on sensor readings.

See also: State Based Behavior, Emotion State

Static Discharge¶

A sudden, uncontrolled flow of static electricity between two objects at different electrical potentials, which can damage sensitive electronic components on contact.

Example: Touching a grounded metal object before handling a Raspberry Pi board helps prevent static discharge from damaging its chips.

Station Mode¶

A wireless configuration in which a device connects to an existing Wi-Fi network as a client, rather than creating its own network.

Example: A Pico W weather-station project configures its wireless chip in station mode, joining the classroom's existing Wi-Fi network rather than creating its own.

Contrast with: Access Point Mode

Stopwatch Feature¶

A clock or watch capability that measures and displays elapsed time starting from the moment a user presses a start control until it is stopped.

Example: A wristwatch project adds a stopwatch feature that starts counting elapsed seconds on the round display the moment a side button is pressed.

Contrast with: Timer Feature

Storage And Inventory¶

The practice of tracking what components a classroom or program currently has on hand and where they are physically stored.

Example: A robotics program keeps a spreadsheet for storage and inventory, tracking how many spare motors and Pico boards remain in the supply closet.

See also: Classroom Kit Organization, Shared Component Bin

Storage Benchmark¶

A test that measures how quickly a storage device, such as a microSD card or NVMe drive, can read and write data.

Example: Chapter 14 has students run a storage benchmark comparing read speeds between a microSD card and an NVMe drive on the same Raspberry Pi 5.

See also: NVMe Storage, MicroSD Storage

Student Portfolio¶

A collected record of a student's projects, code, and reflections over time, used to document learning progress and achievement.

Example: By the end of the book, a student's digital portfolio includes photos and code from their NeoPixel art piece, STEM robot, and capstone project.

See also: Assessment Rubric, Portfolio Artifact

Sudo Command¶

A command that temporarily grants a regular user root-level permissions to run a single command that would otherwise be blocked.

Example: Running sudo apt update with the sudo command allows a regular user account to update the system's software package list.

See also: Root User, Install Package Command

Supply Chain Shortage¶

A situation in which a component becomes difficult or impossible to purchase due to manufacturing or distribution problems affecting its availability.

Example: A teacher switches from a preferred Pico supplier to a backup one after a supply chain shortage delays an order needed before the robot unit begins.

See also: Lead Time, Component Substitution

Swarm Robotics¶

An approach to robotics in which multiple simple robots coordinate their behavior, often through wireless communication, to accomplish a task together.

Example: In a swarm robotics demonstration, several Pico W robots share their positions over Wi-Fi so they can spread out evenly across a room.

See also: Peer To Peer Communication

System Configuration Tool¶

A utility, such as raspi-config on Raspberry Pi OS, that provides a guided menu for adjusting system-wide settings like interfaces, locale, and boot options.

Example: A student opens the raspi-config system configuration tool on their Pi 500+ to enable the I2C interface needed for a DS3231 clock project.

See also: Raspberry Pi OS

System On Chip¶

A single chip that integrates a processor, memory controller, graphics processing, and other major computing components that would otherwise require several separate chips.

Example: The Broadcom BCM2712 system on chip inside the Raspberry Pi 5 combines the CPU, GPU, and memory controller in one package.

Task Manager¶

A tool, graphical or text-based, that lists currently running programs on a computer and allows a user to monitor or stop them.

Example: A student opens a graphical task manager on their Pi 500+ desktop to find and close a Python script that stopped responding.

See also: Process Management

Technical Documentation¶

Written material that explains how a project works, how it was built, and how to use or modify it.

Example: A capstone team writes technical documentation explaining how their NeoPixel alert system is wired and how to modify its Python code.

See also: README File

Temperature Sensor¶

A sensor that measures the surrounding air or surface temperature and reports it as an electrical signal or digital value.

Example: A temperature sensor built into a DHT11 module lets a program display the current room temperature on an OLED screen.

See also: DHT11 Sensor

Terminal Emulator¶

An application that displays a text-based command line interface, letting a user type and run commands directly to the operating system.

Example: A student opens a terminal emulator window on the Pi 500+ desktop to type Linux commands for installing a new library.

Contrast with: File Manager

See also: Command Line Interface, Shell

Text To Speech¶

A technology that converts written text into a synthesized, spoken audio output.

Example: A text to speech system reads a robot's detected object label aloud through a small speaker.

Contrast with: Speech To Text

TFLite Model Format¶

A compact machine learning model file format, based on TensorFlow, designed specifically for efficient inference on small, low-power devices.

Example: A lightweight sound-classification model for the chapter-18 project is distributed in the TFLite model format so it runs efficiently on a Raspberry Pi without heavy hardware.

Contrast with: ONNX Model Format

See also: Model Compression

TFT Display¶

A full-color liquid crystal display technology that uses an active transistor grid to control each pixel individually, producing sharper, faster-updating images than simple LCD character displays.

Example: The chapter-9 clock unit uses a full-color TFT display driven by an ILI9341 chip to show a colorful digital watch face instead of simple monochrome text.

See also: ILI9341 Driver, Round Display

Thermal Throttling¶

An automatic reduction in a processor's clock speed, triggered when it becomes too hot, to prevent damage at the cost of reduced performance.

Example: Without the Active Cooler attached, a Raspberry Pi 5 running the AI HAT+ object-detection demo for several minutes can hit thermal throttling, slowing its frame rate.

See also: Active Cooling, Clock Speed

Thonny IDE¶

A beginner-friendly integrated development environment used to write, run, and debug MicroPython code on a Raspberry Pi Pico.

Example: Students use Thonny IDE to upload a MicroPython script to their Pico and watch its output in the built-in console.

See also: MicroPython

Threshold Value¶

A specific numeric boundary chosen in a program to decide when a sensor reading should trigger a change in behavior.

Example: A robot's obstacle-avoidance code stops the motors when a distance reading falls below a threshold value of 10 centimeters.

See also: Calibration

Tilt Switch¶

A sensor that opens or closes an internal circuit depending on the angle at which it is held, often using a small rolling ball or metal sphere inside.

Example: Tilting a wearable device forward closes the tilt switch and triggers a NeoPixel to flash.

See also: Momentary Switch

Time Formatting Code¶

Program logic that converts a raw time value into a readable text string, such as adding a leading zero or a colon separator between hours and minutes.

Example: A digital clock project's time formatting code adds a leading zero so "9:05" displays correctly instead of showing "9:5" on the LCD1602.

See also: Epoch Time, Digital Clock Format

Time Of Flight Sensor¶

A distance sensor that measures how long it takes a pulse of light, usually infrared laser light, to travel to an object and reflect back, calculating distance from that travel time.

Example: A time of flight sensor can measure distance more precisely than an ultrasonic sensor in small, tight spaces.

Contrast with: Ultrasonic Sensor

See also: Distance Measurement

Time Zone Offset¶

The number of hours, and sometimes minutes, that a local time differs from a reference time such as Coordinated Universal Time.

Example: A clock project adds a time zone offset of negative five hours to convert Coordinated Universal Time into Eastern Standard Time.

See also: Daylight Saving Time

Timekeeping Accuracy¶

A measure of how closely a clock's reported time matches true elapsed time, often expressed as the number of seconds a clock may drift per day or month.

Example: A DS3231 module offers much better timekeeping accuracy than a Pico's built-in clock, drifting only a couple of seconds per month instead of several minutes.

See also: Real Time Clock, NTP Time Sync

Timer Feature¶

A clock or watch capability that counts down from a set duration to zero and then signals the user, rather than counting up from zero like a stopwatch.

Example: A wristwatch project's timer feature counts down from a five-minute study break and beeps the piezo buzzer once it reaches zero.

Contrast with: Stopwatch Feature

See also: Alarm Feature

TM1637 Driver¶

A common controller chip used to drive small seven segment displays, allowing a microcontroller to set the displayed digits using just two signal wires.

Example: A seven-segment clock project uses a TM1637 driver chip to display digits using only two signal wires from the Pico.

See also: Seven Segment Display

Tone Generation¶

The process of producing a specific musical pitch by driving a buzzer or speaker with a signal at a chosen frequency.

Example: Tone generation code sends a 440 Hz signal to a passive buzzer to play the musical note A.

See also: Passive Buzzer

TOPS Performance Metric¶

Trillions of Operations Per Second, a benchmark number used to describe how much raw computing throughput a neural processing unit can deliver.

Example: The AI HAT+ chapter cites a TOPS performance metric to compare how much raw computing throughput the Hailo accelerator adds versus the Pi 5's CPU alone.

See also: Neural Processing Unit

Total Cost Of Ownership¶

The full cost of using a piece of hardware over its useful life, including the purchase price plus accessories, power supplies, storage, replacement parts, and maintenance time.

Example: A Raspberry Pi 5's total cost of ownership includes not just the board but also a power supply, microSD card, and case.

See also: Price Tier, Cost Per Student

Training Dataset¶

The portion of a labeled dataset actually used to adjust a machine learning model's parameters during model training.

Example: Chapter 16's example splits its collected photos into a training dataset used to teach the model and a separate validation dataset used to check its accuracy afterward.

Contrast with: Validation Dataset

Training Versus Inference¶

The distinction between building a machine learning model by learning from data, called training, and using that already-built model to make predictions, called inference.

Example: Training a new object-detection model typically happens on a powerful computer, while inference then runs efficiently on the Raspberry Pi 5's AI HAT+.

See also: Model Training, Model Inference

Transfer Learning¶

A technique that starts from a pretrained model and retrains only part of it on new, smaller data, allowing a custom model to be built faster than training entirely from scratch.

Example: Instead of training an object-detection model from scratch, chapter 16 introduces transfer learning, starting from a pretrained model and retraining only the final layers to recognize a custom set of classroom objects.

See also: Pretrained Model, Custom Object Class

Trial And Error Testing¶

A problem-solving approach that involves trying a possible solution, observing the result, and adjusting the approach based on what happened, repeating until the problem is solved.

Example: A student unsure of a resistor's value tries a 220-ohm resistor, observes the LED is too dim, and tries a smaller value instead.

Turning Radius¶

The size of the circular path a robot follows while turning, which becomes smaller when the difference in speed between its left and right motors increases.

Example: Stopping the left motor entirely while the right motor keeps spinning produces the smallest possible turning radius, pivoting the robot roughly in place.

See also: Differential Drive

Typing Speed Indicator¶

A lighting effect that changes a keyboard's colors or animation speed based on how quickly a user is currently typing.

Example: A Pi 500+ script acts as a typing speed indicator, shifting the keyboard's lighting animation from calm blue to energetic red as a student types faster.

See also: Reactive Lighting

Ultrasonic Sensor¶

A distance sensor that emits a high-frequency sound pulse and measures the time it takes for the echo to return, using that time to calculate distance to the nearest object.

Example: An ultrasonic sensor mounted on a robot's front bumper reports that a wall is 15 centimeters away.

Contrast with: Time Of Flight Sensor

See also: Distance Measurement

Update System Command¶

The pair of commands, typically sudo apt update followed by sudo apt upgrade, used to refresh the list of available software and install the latest versions.

Example: A student runs the update system command sudo apt update && sudo apt upgrade before installing new libraries for the AI HAT+ chapter.

See also: APT Package Manager, Software Update

USB 3.0 Port¶

A Universal Serial Bus connector supporting significantly faster data transfer speeds than earlier USB versions, used on the Raspberry Pi 5 for external drives and peripherals.

Example: A student plugs an external SSD into the Raspberry Pi 5's USB 3.0 port to get faster file transfer speeds than the microSD card allows.

USB C Power Delivery¶

A standard that allows a USB-C cable and power supply to negotiate and deliver higher voltages and currents than a basic USB connection, used to power the Raspberry Pi 5.

Example: The Raspberry Pi 5 relies on USB-C Power Delivery to draw the higher wattage it needs when running the AI HAT+ and Active Cooler together.

See also: Power Supply Rating

USB HID Protocol¶

Universal Serial Bus Human Interface Device protocol, the standard method by which keyboards, mice, and similar input devices communicate key and button events to a computer.

Example: The Raspberry Pi 500+'s keyboard communicates key presses to the operating system using the standard USB HID protocol, the same one an external mouse uses.

See also: Human Interface Device

USB Microphone¶

A microphone that connects to a computer through a USB port, providing a digital audio signal without requiring a separate audio interface.

Example: A chapter-18 sound-classification project plugs a USB microphone into the Raspberry Pi 5 to capture audio clips without needing a separate sound card.

See also: Microphone Module

User Testing¶

The process of having someone other than the builder try a finished or in-progress project, in order to find problems and gather feedback.

Example: A capstone team asks a classmate unfamiliar with their code to try their NeoPixel alert device during user testing, uncovering that the button was too easy to miss.

See also: Prototype Iteration, Peer Code Review

Validation Dataset¶

A separate portion of a labeled dataset, kept apart from the training dataset, used to check how well a machine learning model performs on data it has not directly learned from.

Example: Chapter 16 checks a sound-classification model's real-world performance using a validation dataset of recordings the model never saw during training.

Contrast with: Training Dataset

See also: Model Accuracy

VCC¶

The label commonly used on components and schematics to mark the pin that supplies positive operating voltage to a circuit.

Example: A sensor module's VCC pin is connected to the Pico's 3.3-volt output so the sensor has power to operate.

See also: Ground, 3.3 Volt Logic

Vendor Comparison¶

The practice of evaluating multiple suppliers of the same component based on price, shipping time, and reliability before making a purchase.

Example: A teacher does a vendor comparison between two suppliers of STEM robot kits, weighing a slightly higher price against faster shipping before the semester starts.

See also: Component Sourcing

Vendor Documentation¶

The official technical guides, datasheets, and reference materials published by a hardware or component manufacturer describing how their product works and should be used.

Example: A student consults the vendor documentation for a DHT11 sensor to learn its exact wiring pinout and timing requirements.

See also: Component Datasheet

Version Control¶

A system for tracking changes made to files over time, allowing a user to review history, revert mistakes, and collaborate without overwriting each other's work.

Example: A capstone team uses version control with Git so they can revert their NeoPixel project's code after an experimental change breaks the light pattern.

See also: Git Basics

Video Stream¶

A continuous sequence of image frames captured by a camera and transmitted or processed in real time.

Example: The chapter-17 object-detection project processes a live video stream from the Camera Module, analyzing each frame as it arrives.

See also: Frame Capture, Real Time Video Pipeline

Visual Feedback Design¶

The practice of designing lighting, animation, or display changes so that a device clearly communicates its current state or response to a user's action.

Example: The OLED chapter emphasizes visual feedback design, having a robot's eyes widen and its buzzer chirp the instant it detects a nearby obstacle so its reaction is obvious to onlookers.

See also: Sound Feedback

VNC Remote Desktop¶

A remote access method that lets a user view and control a computer's full graphical desktop over a network, rather than just its command line.

Example: A student uses VNC remote desktop to see and control their headless Raspberry Pi 5's full graphical desktop from a laptop, not just its command line.

Contrast with: SSH Protocol, which provides only command line access.

See also: Remote Login

Voice Command¶

A spoken instruction that a device recognizes and converts into a specific action, such as turning on an LED or starting a robot.

Example: A capstone robot responds to the voice command "stop" by immediately halting both motors, detected through the chapter-18 sound-classification pipeline.

See also: Speech To Text, Wake Word Detection

3.3 Volt Logic¶

A signaling standard in which digital high and low states are represented by roughly 3.3 volts and 0 volts, used by the Raspberry Pi Pico and Raspberry Pi 5 GPIO pins.

Example: Connecting a 5-volt sensor directly to a Pico's 3.3 volt logic input can damage the pin, so a voltage divider or level shifter is needed.

Voltage¶

The electrical potential difference between two points in a circuit, which pushes current to flow and is measured in volts.

Example: A Raspberry Pi Pico's GPIO pins operate at a voltage of 3.3 volts, not the 5 volts used on some other boards.

See also: Current, Resistance, Ohms Law

Voltage Divider¶

A simple circuit made from two resistances in series that splits an input voltage into a smaller output voltage, proportional to the ratio between the two resistances.

Example: A voltage divider built from a fixed resistor and a photoresistor produces a voltage that rises and falls as room light changes.

See also: Photoresistor, Analog Read

Voltage Regulator¶

A component that takes an input voltage that may vary or be too high and outputs a steady, fixed voltage suitable for powering sensitive electronics.

Example: A voltage regulator steps a battery pack's fluctuating 6 volts down to a steady 3.3 volts to safely power a Pico.

VS Code On Pi¶

A version of the popular Visual Studio Code editor that runs directly on Raspberry Pi computers, used for writing and debugging Python and other code.

Example: A student installs VS Code on Pi to write and debug their chapter-17 object-detection Python script with syntax highlighting and inline error checking.

See also: Code Editor

Wake Word Detection¶

A form of keyword spotting that listens continuously for a specific trigger phrase, activating fuller voice command processing only after that phrase is heard.

Example: A voice-controlled NeoPixel project uses wake word detection, staying idle until it hears "hey lights" before listening for a full color command.

See also: Keyword Spotting, Voice Command

Watch Face Design¶

The process of laying out the visual elements, such as hands, numerals, or digits, that make up the display of a digital or analog-style clock or watch project.

Example: In the wearables chapter, a student sketches watch face design options for their round-display project, choosing between a digital numeral layout and hands like a traditional analog watch.

See also: Round Display, Analog Clock Hands

Wearable Electronics¶

Electronic circuits and components designed to be worn on the body, typically built to be compact, lightweight, and durable enough for movement.

Example: A NeoPixel bracelet that lights up in sync with music is a piece of wearable electronics.

See also: Wearable Enclosure

Wearable Enclosure¶

A protective case or housing, often 3D printed or built from a kit, that holds a wearable project's electronics and display securely against or near the body.

Example: A 3D-printed wearable enclosure holds a DS3231 module, Pico, and round display securely against a student's wrist for the chapter-9 watch project.

See also: Wearable Electronics, Wristband Mounting

Web Server¶

A program that listens for incoming HTTP requests and responds with data, such as a webpage or sensor reading, over a network.

Example: A tiny web server running on a Pico W lets a phone's browser turn a NeoPixel on and off by visiting a specific address.

See also: HTTP Protocol, REST Endpoint

Wheel Alignment¶

The adjustment of a robot's wheels so they are mounted straight and even, preventing the robot from drifting to one side when both motors run at equal speed.

Example: Poor wheel alignment can make a robot curve left even when its code commands it to drive perfectly straight.

Wheel Encoder¶

A sensor attached to a motor or wheel that detects rotation, allowing a robot to measure how far or how fast a wheel has turned.

Example: A wheel encoder lets a robot count exact rotations so it can travel a precise distance rather than just running the motor for a fixed time.

Wi-Fi¶

A wireless networking technology that allows devices to connect to a local network and the internet without physical cables, using radio signals.

Example: A Pico W connects to a home Wi-Fi network to check the current weather online.

See also: Wi-Fi Credentials, Network SSID

Wi-Fi Credentials¶

The network name and password required for a device to authenticate and join a specific Wi-Fi network.

Example: A Pico W weather-station script needs the classroom's Wi-Fi credentials, network name and password, hard-coded or entered before it can publish sensor readings over MQTT.

See also: Wi-Fi, Network SSID

Window Manager¶

The part of a desktop environment responsible for positioning, resizing, and controlling the appearance of application windows on screen.

Example: The window manager in Raspberry Pi OS's desktop environment lets a student drag a terminal window to one side of the screen and a code editor to the other.

See also: Desktop Environment

Wire Color Convention¶

A common, informal practice of using specific wire colors, such as red for positive power and black for ground, to make circuits easier to read and troubleshoot.

Example: Following wire color convention, a student uses a black jumper wire for every ground connection on a breadboard project.

Wireless Module¶

A hardware component that adds wireless communication capability, such as Wi-Fi or Bluetooth, to a microcontroller board.

Example: The CYW43 wireless module built into the Pico W is what separates it from a standard Pico, adding Wi-Fi and Bluetooth Low Energy capability.

See also: CYW43 Chip

Wireless Range¶

The maximum distance over which a wireless device can maintain a reliable connection to a network or another device.

Example: A student testing a Pico W sensor project outdoors finds its wireless range only reliably reaches about 30 meters from the classroom Wi-Fi router.

See also: Network Latency

Working Directory¶

The folder location a shell currently considers "here," used as the starting point for any file or folder name typed without a full path.

Example: Running ls without any arguments lists the files in the current working directory.

See also: Change Directory Command

Wristband Mounting¶

The hardware and design approach used to attach a wearable project's enclosure securely to a strap worn around the wrist.

Example: A chapter-9 wearable project uses simple slot-and-strap wristband mounting to attach its 3D-printed enclosure to a standard watch band.

See also: Wearable Enclosure, Custom Watch Strap

WS2812B LED¶

A specific integrated circuit LED chip that combines red, green, and blue emitters with a controller, allowing many of them to be chained and individually addressed over one data wire.

Example: Each individually addressable pixel on the chapter-5 NeoPixel strip is a WS2812B LED, combining red, green, and blue emitters with its own tiny controller chip.

See also: NeoPixel, Addressable LED, Chained LED Protocol

Glossary of Terms¶

Abstraction¶

Access Point Mode¶

Accessibility Lighting Cue¶

Active Buzzer¶

Active Cooling¶

Actuator¶

Addressable LED¶

AI HAT Plus¶

Alarm Feature¶

Alert Sound Trigger¶

Algorithm¶

Algorithm Design¶

Ambient Lighting Mode¶

Amplifier Module¶

Analog Audio Signal¶

Analog Clock Hands¶

Analog Pin¶

Analog Read¶

Analog To Digital Converter¶

Animation Frame¶

Animation Timing¶

APT Package Manager¶

Assessment Rubric¶

Audio Buffer¶

Audio Confidence Score¶

Audio Feature Extraction¶

Audio Latency¶

Audio Model Inference¶

Audio Preprocessing Pipeline¶

Audio Privacy Considerations¶

Audio Sampling Rate¶

Autofocus Camera¶

Autonomous Navigation¶

Bash Shell¶

Battery Life Optimization¶

Battery Pack¶

Battery Safety¶

Behavior Tree¶

Bill Of Materials¶

BLE Advertising¶

BLE Central¶

BLE Characteristic¶

BLE Peripheral¶

BLE Service¶

Blink An LED¶

Blink Animation¶

Bluetooth Low Energy¶

Boot Process¶

Bounding Box¶

Breadboard¶

Breadboard Rail¶

Breadboard Row¶

Brightness¶

Brightness Scaling¶

Broadcom BCM2712¶

Bulk Discount¶

Bulk Purchasing¶

Button Debounce Code¶

Buzzer Melody¶

Calibration¶

Camera Module¶

Camera Resolution¶

Camera Serial Interface¶

Camera To Model Pipeline¶

Capacitor¶

Capstone Project¶

Captive Portal¶

Case And Ventilation¶

Chained LED Protocol¶

Change Directory Command¶

Chase Animation¶

Chassis Assembly¶

Chmod Command¶

Chown Command¶

Circuit Diagram¶

Class Label¶

Classroom Budget¶

Classroom Kit Organization¶

Classroom Time Management¶