Glossary of Terms¶

Agent Approval Rules¶

Settings that require a person to confirm certain actions before the agent performs them.

Example: The agent asks for confirmation before enabling always-on listening.

Agent Configuration File¶

A file containing the settings that define an agent's behavior.

Example: It lists the calendar source and allowed tools.

Agent Data Flow¶

The path that information takes from a spoken question through the device to the agent and back to the speaker and display.

Example: Microphone, Pico, Wi-Fi, buddy server, reply text, speaker output.

Agent Memory¶

Information an agent keeps between requests so it can use earlier facts or preferences.

Example: The agent remembers a student's preferred reminder time.

Agent Permissions¶

The limits on what an agent is allowed to access or do.

Example: The agent may read the calendar but not send email.

Agent Progression Levels¶

The staged path from a simple rule-based server, to one using speech services and a language model, to an optional self-hosted open-source agent.

Example: Level 1 matches keywords; level 2 adds one LLM call.

Agent Terminal¶

The small device that gives an agent a face, voice, ears, and buttons while the agent's thinking happens elsewhere.

Example: The Pico acts as an agent terminal by sending recorded speech out and showing the reply.

Agent Tools¶

Functions an agent can call to get information or take action, such as looking up a calendar.

Example: An "upcoming events" tool returns the next three calendar entries.

Alert Message Format¶

The agreed structure of an alert sent over MQTT.

Example: JSON with a title, date, and category.

Aliasing¶

False low frequencies that appear when a signal contains frequencies above the Nyquist limit.

Example: A 10,000 Hz tone sampled at 16,000 Hz appears as 6,000 Hz.

Always-On Approval Process¶

The steps needed to approve continuous listening.

Example: Request, review, written approval, then enable.

Always-On Device¶

A device that stays powered and ready so it can respond at any moment.

Example: A desk buddy plugged into USB power waits for a button press all day.

Always-On Listening¶

A mode in which the microphone constantly monitors for the wake word.

Example: Always-on listening requires explicit approval from a parent or school.

Contrast with: Push-to-Talk

Amplifier Shutdown Pin¶

A pin that turns the amplifier output on or off.

Example: The program pulls the pin low to silence the speaker.

Amplitude¶

The size of a wave's swing, which relates to loudness.

Example: A louder tone has greater amplitude.

Analog to Digital Conversion¶

Turning a continuous electrical signal into numbers.

Example: The microphone chip performs the conversion before sending data to the Pico.

Animation¶

A sequence of changing images that creates an impression of motion.

Example: Spectrum bars rise and fall with the sound.

Array Passed By Address¶

Giving a function the memory location of an array so no copy is made.

Example: Assembly code receives the address of the audio buffer.

Assembly FFT¶

An FFT whose inner loop is written in assembly for speed.

Example: The assembly FFT fits inside the frame time budget.

Audio Buffer¶

A block of memory that holds a group of audio samples.

Example: A 1,024-sample buffer is processed each frame.

Audio Chunk Size¶

The number of bytes sent in each piece of an upload.

Example: A 4,096-byte chunk size balances memory use and speed.

Audio Clipping¶

Distortion that occurs when a signal exceeds the largest value that can be represented.

Example: A very loud sound flattens at the maximum sample value.

Audio Frame¶

A group of consecutive samples processed together.

Example: A 512-sample frame at 16,000 Hz lasts 32 ms.

Audio Not Stored¶

A design in which audio is discarded after use.

Example: Only the text reply is kept.

Authentication Token¶

A secret string that proves a device is allowed to use a service.

Example: The device sends its token in a request header.

Avoiding Allocation¶

Writing code that creates no new objects inside time-critical loops.

Example: Reusing one buffer prevents garbage collection pauses.

Backlight Control¶

Adjusting the brightness of the light behind the display.

Example: The device dims the backlight at night.

Band Energy¶

The total strength within a range of frequencies.

Example: The bass band sums bins from 0 to 250 Hz.

Barge-In Interruption¶

A user interrupting the device while it is speaking.

Example: Pressing Mode stops the spoken reply.

Benchmarking¶

Measuring performance under controlled, repeatable conditions.

Example: Run each FFT version 100 times and compare averages.

Bin Width¶

The frequency range covered by one bin, equal to the sample rate divided by the FFT size.

Example: 16,000 Hz divided by 512 gives 31.25 Hz.

Bit Clock¶

The I2S signal that marks when each data bit is valid.

Example: The bit clock ticks once per transmitted bit.

Bit Depth¶

The number of bits used to store each sample.

Example: 16-bit samples have 65,536 possible values.

Bit-Reversal Table¶

A lookup table that reorders samples for the FFT.

Example: Index 1 in a 8-point FFT maps to index 4.

Boot and Main Scripts¶

The two files MicroPython runs at startup: boot.py first for setup, then main.py for the program.

Example: main.py starts the device loop after power-up.

Breadboard¶

A reusable board with connected holes for building circuits without soldering.

Example: The display and microphone wires plug into a breadboard.

Broker Exposure Risk¶

The danger of making an MQTT broker reachable from the public internet.

Example: An open broker lets strangers send alerts.

Broker on Raspberry Pi¶

Running the MQTT broker software on a Raspberry Pi.

Example: A Pi in the library hosts Mosquitto.

Buddy Server¶

A program on the school network that receives requests from the device and returns replies, optionally using speech services or a language model.

Example: A 100-line buddy server answers "What is due?" from a JSON file.

Button Debouncing¶

Filtering out the rapid false presses that occur as a switch settles.

Example: The code ignores changes for 20 ms after an edge.

Button Interrupt¶

An interrupt triggered by a button pin change.

Example: A button interrupt records a press even while the display is drawing.

Byte Arrays¶

Mutable sequences of bytes that hold raw data such as audio samples.

Example: bytearray(1024) creates a 1,024-byte audio buffer.

Calendar Polling¶

Checking a calendar source at regular intervals.

Example: The server fetches the ICS feed every 15 minutes.

Calibration Config Value¶

A stored setting produced by calibration.

Example: NOISE_FLOOR = 120 in the config file.

Capstone Project¶

A final project that combines the skills from the course.

Example: A homework-reminder buddy for a class.

Certificate Handling¶

Checking or storing the digital certificate that proves a server's identity.

Example: The device verifies the server certificate before sending data.

Chatbot Versus Agent¶

A comparison between software that only answers one message at a time and software that plans and performs several steps toward a goal.

Example: A chatbot explains what a calendar is; an agent reads your calendar and tells you what is due.

check_msg Polling¶

Calling check_msg to process incoming MQTT messages without blocking.

Example: The audio loop calls check_msg once per frame.

Chunked Audio Upload¶

Sending audio to a server in small pieces instead of one large block.

Example: The Pico sends 4 KB chunks to stay within memory limits.

Clap Detector¶

A program that detects a sudden loud sound pattern.

Example: A clap toggles the display light.

Class-D Amplifier¶

An efficient amplifier that switches its output on and off rapidly to reproduce sound.

Example: The MAX98357A is a Class-D amplifier, so it stays cool at low volume.

Classroom Noise Monitor¶

A device feature that measures and displays room loudness.

Example: The screen turns red when the room is too loud.

Clipping Detection¶

Checking whether samples reach the maximum possible value.

Example: A warning appears when many samples are clipped.

Clock Face Geometry¶

The math for placing marks and hands on a circular clock.

Example: Twelve tick marks are spaced 30 degrees apart.

Cloud Agent¶

An agent that runs on a vendor's remote computers and is usually reached over the internet for a recurring fee.

Example: A subscription assistant that stores your messages on the vendor's servers is a cloud agent.

Contrast with: Self-Hosted Agent

Color Themes¶

Named sets of colors applied consistently across the interface.

Example: A school theme uses its team colors for the background and digits.

Config File Pattern¶

A practice of keeping settings such as Wi-Fi names and server addresses in a separate file instead of in program logic.

Example: A config.py file holds the server address.

Permission freely given by a person to collect or use their data.

Example: A parent signs a form before always-on listening.

Cortex-M33 Core¶

The ARM processor design used in the RP2350 that includes instructions helpful for signal processing.

Example: Assembly code uses Cortex-M33 instructions to speed up the FFT.

Course Information¶

Details about classes that the agent can report.

Example: The next class meets in room 204.

Custom Wake Phrase¶

A wake phrase chosen by a school or student.

Example: "Hey Griffin" replaces "Hey Pico."

Cycle Counter¶

A hardware register that counts processor clock cycles.

Example: Reading it before and after code reveals how many cycles were used.

Daily Briefing¶

A morning summary of the day's events.

Example: "Today you have one test and one project due."

Data Minimization¶

Collecting only the data needed for a task.

Example: Send only the recorded question, not continuous audio.

Data Retention¶

How long collected data is kept.

Example: Transcripts are deleted after one day.

DC Offset Removal¶

Subtracting the average value from a signal so it centers on zero.

Example: Removing the offset prevents a false strong low-frequency bin.

Decibels¶

A logarithmic unit for comparing signal strengths.

Example: Doubling amplitude adds about 6 dB.

Detection Threshold¶

The score above which the detector reports the wake word.

Example: A threshold of 0.8 requires a close match.

Detector Math Test¶

A test that runs the scoring calculation on known numbers.

Example: Identical vectors must score near 1.

Detector Self-Test¶

A built-in check that confirms the wake-word code works.

Example: The device plays a stored sample and expects a detection.

Device Modes¶

The distinct behaviors the device can be in, such as clock, listening, thinking, speaking, and settings.

Example: In listening mode the display shows a live spectrum.

Device Status Topic¶

A topic where a device reports its condition.

Example: school/room12/pico1/status carries online or offline.

Diagnosing Blank Display¶

Finding why the screen shows nothing.

Example: Check power, SPI wiring, and backlight pin.

Diagnosing Distorted Audio¶

Finding why sound is crackly or harsh.

Example: Look for clipping or buffer underruns.

Diagnosing Silent Microphone¶

Finding why the microphone produces no sound.

Example: Check the left-right select wire and I2S pins.

Direct Region Write¶

Sending pixels only for a chosen rectangle of the screen instead of the whole frame.

Example: Redrawing just the clock digits after a minute change.

Dirty Region¶

The part of the screen that has changed and needs redrawing.

Example: A spectrum bar that grew is marked as a dirty region.

Discrete Fourier Transform¶

The Fourier transform applied to a finite list of samples.

Example: A DFT of 512 samples gives frequency values for 512 bins.

Display Controller¶

The chip inside a screen module that receives commands and pixel data and drives the panel.

Example: The controller accepts a window command followed by pixel data.

Display Refresh Rate¶

How many times per second the screen image is updated.

Example: A spectrum display aims for a smooth number of updates per second.

Dot Product Score¶

A sum of products of matching values that measures similarity.

Example: The detector multiplies feature and template values and adds them.

Down Button¶

The button that lowers a value or moves down in a menu.

Example: Down lowers the speaker volume.

Drawing Window¶

The rectangle on the display that incoming pixel data fills.

Example: The code sets a window, then streams the pixels for that area.

Dual Core Processor¶

A processor with two cores that can run separate tasks at the same time.

Example: One core handles audio while the other updates the display.

Dual Core Use¶

Assigning different tasks to the two processor cores.

Example: Core 1 computes the FFT while core 0 handles the network.

Dupont Wires¶

Plug-in jumper wires with connector ends used to link parts on a breadboard.

Example: Dupont wires link the microphone's pins to the Pico.

DWT Timer¶

The Cortex-M debug counter that supplies a cycle count.

Example: The DWT timer measures an FFT in cycles.

Edge Device¶

A small computer that works at the place where data is collected, such as a classroom desk, rather than in a data center.

Example: The Pico captures microphone audio at the edge before sending it onward.

Event Categories¶

Groups that classify events by kind.

Example: Categories include test, due, and general.

Event Loop¶

A main loop that repeatedly checks for events and handles them.

Example: The loop checks buttons, audio, and network messages in turn.

Event Parsing¶

Reading event text and extracting its date, title, and category.

Example: The server turns an ICS entry into a structured event.

Events JSON File¶

A hand-edited file that lists events in JSON.

Example: A teacher adds a TEST entry to the file.

Exceptions¶

Error objects raised when a program cannot continue normally, which can be caught and handled.

Example: A failed Wi-Fi connection raises an exception that the code catches and retries.

Falling Edge Detection¶

Noticing the moment an input changes from high to low.

Example: A falling edge marks the instant a pulled-up button is pressed.

False Accept¶

A detection reported when the wake word was not spoken.

Example: A cough triggers the device.

False Reject¶

A missed detection when the wake word was spoken.

Example: "Hey Pico" said quickly is ignored.

Feature Extraction¶

Converting raw audio into a smaller set of numbers that describe it.

Example: Band energies from each frame form the feature vector.

FFT¶

A fast algorithm for computing the discrete Fourier transform.

Example: The FFT turns each audio frame into a spectrum in real time.

FFT Size¶

The number of samples fed to one FFT.

Example: An FFT size of 512 uses 512 samples.

Fixed-Point Math¶

Using integers with an implied decimal point to represent fractions.

Example: A value of 1.5 is stored as 384 with 8 fractional bits.

Flash File System¶

The storage area in a board's flash memory that holds program and data files.

Example: Scripts and images are saved in the Pico's flash file system.

Floating Point Cost¶

The extra time that decimal-number math takes compared with integer math.

Example: Floating point FFT arithmetic is slower than fixed-point.

Fonts¶

Sets of character shapes used when drawing text.

Example: A larger font makes the time readable from across a desk.

Fourier Transform¶

A mathematical method that converts a signal from time domain to frequency domain.

Example: It reveals that a signal is mostly a 440 Hz tone.

Frame Buffer¶

A block of memory holding the color of every pixel for one screen image.

Example: A full RGB565 frame buffer for this display is about 259 KB.

Frame Overrun¶

A frame whose processing takes longer than its time budget.

Example: An overrun causes the next audio frame to be missed.

Frame Overrun Counter¶

A count of how many frames took longer than their budget.

Example: A rising counter shows the code is too slow.

Frame Size Calculation¶

The arithmetic that multiplies width, height, and bytes per pixel to find the memory a frame needs.

Example: 360 × 360 × 2 bytes equals 259,200 bytes.

Frame Time Budget¶

The time available to finish processing one audio frame before the next arrives.

Example: A 32 ms frame leaves 32 ms for the FFT and drawing.

Frequency¶

How many times per second a repeating wave completes a cycle, measured in hertz.

Example: Middle A has a frequency of 440 Hz.

Frequency Bin¶

One slot of an FFT result that represents a narrow range of frequencies.

Example: Bin 10 represents frequencies near ten bin-widths.

Frequency Domain¶

A view of a signal as the strength of each frequency it contains.

Example: A spectrum plot shows the frequency domain.

Full-Frame Update¶

Redrawing every pixel of the screen for each change.

Example: Sending 259 KB to change one digit is a full-frame update.

Contrast with: Direct Region Write

Garbage Collection¶

Automatic cleanup in which the runtime frees memory that a program no longer uses.

Example: A garbage collection pause can cause a brief audio glitch.

Google Calendar API¶

A web interface for reading Google Calendar data.

Example: The server uses it to read class events.

GPIO Pin¶

A general-purpose connection on a microcontroller that a program can set as an input or output.

Example: GPIO 15 is configured as an input for a button.

Ground Wiring¶

The shared return connections that give all parts the same zero-volt reference.

Example: Every module's ground pin connects to a Pico ground pin.

Hand Drawing¶

Drawing a clock hand as a line from the center to a computed endpoint.

Example: The minute hand is redrawn when the minute changes.

Hann Window¶

A bell-shaped window function that tapers smoothly to zero at both ends.

Example: Each frame is multiplied by a Hann window.

Hardware Mute Switch¶

A physical switch that cuts the microphone off.

Example: Sliding the switch ensures no audio is captured.

Heap Fragmentation¶

A condition in which free memory is split into pieces too small to satisfy a large request.

Example: A program fails to allocate a 4 KB buffer even though total free memory is larger.

Hey Pico Phrase¶

The default wake phrase for the device.

Example: Saying "Hey Pico" triggers a confirmation beep.

Home Assistant¶

An open-source home-automation platform that can use MQTT.

Example: Home Assistant shows device status on a dashboard.

Home Automation¶

Using networked devices to control or monitor a building.

Example: A message turns on a light when a test is tomorrow.

Homework Reminder Buddy¶

A buddy that announces homework due dates for a class.

Example: It says "Math worksheet due tomorrow."

HTTP POST¶

An HTTP request that sends data to a server.

Example: The device POSTs a JSON question.

HTTP Protocol¶

The rules web clients and servers use to exchange requests and responses.

Example: The Pico sends an HTTP request to the buddy server.

HTTPS¶

HTTP carried over TLS encryption.

Example: https:// addresses use TLS.

I2S Bus¶

A three-wire serial connection designed for digital audio.

Example: The microphone and amplifier both connect over I2S.

I2S Receive¶

Reading audio data in from an I2S device.

Example: The Pico receives microphone samples.

I2S Transmit¶

Sending audio data out to an I2S device.

Example: The Pico transmits tone samples to the amplifier.

iCalendar Format¶

A standard text format for calendar events.

Example: An .ics file uses the iCalendar format.

Icons¶

Small pictures that represent a status or action.

Example: A speaker icon shows when the device is talking.

ICS Feed¶

A web address that supplies calendar events in iCalendar format.

Example: The server downloads the school's ICS feed.

Image Loading¶

Reading an image file from storage and preparing its pixels for the display.

Example: The mascot image is loaded from flash at startup.

In-Place Transform¶

An algorithm that overwrites its input with its output instead of using a second array.

Example: The FFT reuses the same buffer to save memory.

Inline Assembly¶

Processor instructions written directly inside a MicroPython function.

Example: An assembly loop multiplies and adds samples.

INMP441 Microphone¶

A digital microphone module that sends audio to a microcontroller over the I2S bus.

Example: The INMP441 supplies the audio used for the FFT and wake-word detection.

Interrupt¶

A hardware signal that pauses the main program so a short handler can respond to an event immediately.

Example: A button press triggers an interrupt without the main loop polling.

Interrupt Service Routine¶

The short function that runs when an interrupt occurs.

Example: An ISR sets a flag that the main loop checks later.

IP Address¶

A number that identifies a device on a network.

Example: The buddy server is at 192.168.1.50.

JSON¶

A text format for structured data using keys and values.

Example: {"text": "What is due?"}

Keep-Alive¶

A periodic signal that tells the broker a client is still connected.

Example: A 60-second keep-alive interval.

Kit Bill of Materials¶

The list of every part needed to build the device, with quantities.

Example: The kit list includes one Pico 2 W, one display, one microphone, and three buttons.

Language and Tone¶

The words and manner the agent uses with students.

Example: Short, friendly sentences.

Last Will¶

A message the broker publishes if a client disconnects unexpectedly.

Example: A device's last will reports it offline.

Left-Right Channel¶

The two sides of a stereo signal, selected by word select.

Example: The microphone is set to send on the left channel.

Level Gate¶

A rule that passes audio only when its level exceeds a threshold.

Example: Recording starts when the level gate opens.

Listening Indicator¶

A visible signal that the microphone is active.

Example: A red ring appears on the display.

LLM-Backed Agent¶

An agent that sends the user's request to a large language model to compose its reply.

Example: The server forwards a transcript and calendar summary to an LLM and speaks the result.

Local Network¶

A network that connects devices in one place, such as a classroom.

Example: The Pico and server share a local network.

Local Versus Cloud Processing¶

A comparison of handling data on nearby equipment versus remote servers.

Example: Wake-word matching is local; transcription may be remote.

Log Magnitude¶

Magnitude converted to a logarithmic scale.

Example: Log magnitude makes quiet and loud frequencies both visible.

Log-Spaced Bands¶

Frequency bands whose widths grow with frequency to match hearing.

Example: Each band spans a doubling of frequency.

Logging¶

Recording messages about what a program does.

Example: The device logs each Wi-Fi retry.

Long Press¶

A button hold longer than a set time that triggers a different action.

Example: Holding Mode for two seconds opens settings.

machine Library¶

The MicroPython module that gives programs access to hardware such as pins, timers, and buses.

Example: from machine import Pin controls a GPIO pin.

machine.I2S Class¶

The MicroPython class that sends and receives I2S audio.

Example: Create an I2S object to read from the microphone.

Magnitude Spectrum¶

A list of how strong each frequency bin is.

Example: Bars on the display show the magnitude spectrum.

MAX98357A Amplifier¶

An I2S digital audio amplifier module that drives a small speaker.

Example: The Pico sends audio samples to the MAX98357A, which powers the speaker.

mDNS Discovery¶

Finding devices by name on a local network without a central server.

Example: The device finds buddy.local.

Mean Subtraction¶

Subtracting the average from a set of values so they center on zero.

Example: Removing the mean prevents loudness alone from raising the score.

Memory Limits¶

The small amount of RAM and flash on a microcontroller that restricts what a program can store.

Example: A 259 KB frame buffer does not fit comfortably in the Pico's RAM alongside other data.

memoryview¶

An object that gives a window into existing memory without copying it.

Example: A memoryview lets code write into part of a buffer in place.

MEMS Microphone¶

A microphone built from a microscopic mechanical structure on a silicon chip.

Example: The INMP441 is a MEMS microphone.

Moving through a list of choices using the buttons.

Example: Up and Down move the highlight, and Mode selects.

MFCC Features¶

Audio features based on a perceptual frequency scale, commonly used in speech recognition.

Example: A trained model might take MFCC features as input.

Mic Distance Effect¶

The change in recorded level as the speaker moves nearer or farther from the microphone.

Example: Speech from across the room is much quieter than speech at 20 cm.

Microphone Calibration¶

Measuring the room and speaker levels to set thresholds.

Example: Calibration records five seconds of silence and a spoken sentence.

MicroPython Review¶

A short refresher of the MicroPython skills the course assumes before building the device.

Example: Flash the Pico, open the REPL, and blink an LED.

mip Package Manager¶

MicroPython's tool for downloading and installing libraries onto a board.

Example: Installing the umqtt library with mip.

Mode Button¶

The button that switches the device between modes or confirms a choice.

Example: Pressing Mode moves from the clock to listening.

Modules and Imports¶

Python files that hold reusable code, and the import statement that loads them into a program.

Example: import time makes the sleep function available.

Mono and Stereo¶

One audio channel versus two channels, left and right.

Example: The kit's microphone records in mono.

Mosquitto¶

An open-source MQTT broker.

Example: Mosquitto runs on a school Raspberry Pi.

mpremote¶

A command-line tool for copying files to, and running code on, a MicroPython board.

Example: mpremote cp main.py : copies a script to the Pico.

MQTT Authentication¶

Using a username and password to control access to the broker.

Example: The broker rejects clients without credentials.

MQTT Broker¶

The server that receives published messages and delivers them to subscribers.

Example: Mosquitto is the broker for the school.

MQTT Protocol¶

A lightweight publish/subscribe messaging protocol for small devices.

Example: A school publishes alerts that many devices receive.

Mute and Resume¶

Pausing audio output or input and later restarting it.

Example: The microphone is muted while the speaker talks.

Network Failure Handling¶

Code that responds safely when a connection fails.

Example: The device shows "Offline" instead of freezing.

Network Station Mode¶

A Wi-Fi mode in which the device joins an existing network as a client.

Example: network.WLAN(network.STA_IF) selects station mode.

Noise Floor¶

The level of background sound present when nobody is speaking.

Example: A quiet room might have a low noise floor RMS value.

Non-Blocking Code¶

Code that never waits long for one task, so other tasks keep running.

Example: Checking for an MQTT message without pausing the audio loop.

Nyquist Limit¶

Half the sample rate, which is the highest frequency a sampled signal can represent correctly.

Example: At 16,000 Hz sampling, the Nyquist limit is 8,000 Hz.

OAuth¶

A standard that lets a program access an account without handling its password.

Example: The server obtains permission to read a calendar through OAuth.

Offline Fallback¶

Behavior that keeps the device useful when the network is unavailable.

Example: The clock keeps working without Wi-Fi.

Open Hardware¶

Physical designs whose specifications are published so anyone can study, build, and modify them.

Example: The kit uses common parts that any student can buy and wire without special licenses.

Open Source Software¶

Software whose source code is published under a license that lets people read, change, and share it.

Example: Mosquitto and MicroPython are open source programs used in this book.

Open Study Buddy Device¶

The desk companion built in this course from a Pico 2 W, round display, microphone, speaker amplifier, and three buttons that listens, shows, and speaks.

Example: Pressing Mode on the device starts a question that appears as text on the round display.

Open-Source Agent Framework¶

A publicly available software toolkit for building agents that use tools, memory, and approval rules.

Example: A school installs a framework on its own server and points the device at it.

Parent and School Approval¶

The permission required from guardians and the school before enabling listening.

Example: Always-on mode stays off until both approve.

Peak Frequency Detection¶

Finding the frequency bin with the greatest magnitude.

Example: A tuner reports the peak frequency of a whistle.

Per-School Customization¶

Adjusting the device and agent for a particular school.

Example: Each school sets its own mascot and calendar.

Performance Trade-Offs¶

Choices in which gaining speed costs something else, such as readability or accuracy.

Example: Assembly is faster but harder to maintain.

Personal Agent¶

Software that carries out multi-step tasks on one person's behalf, such as checking calendars, summarizing information, and returning when it needs a decision.

Example: A personal agent notices a test on Friday and reminds you on Thursday evening.

Pin Assignment Table¶

A table that lists which Pico pin connects to each part signal.

Example: The table shows that the speaker amplifier uses specific I2S pins.

Pixel¶

The smallest individually colored dot on a display.

Example: The round display has 129,600 pixels.

Plain HTTP LAN Use¶

Using unencrypted HTTP only on a trusted classroom network.

Example: A lab with no outside access may use plain HTTP.

Polar to Cartesian¶

Converting an angle and distance from a center into x and y coordinates.

Example: A clock hand's tip is found from its angle and length.

Power Supply Noise¶

Unwanted electrical variation on a power line that can leak into audio.

Example: Display activity can add a faint hum to the speaker output.

Pre-Allocated Buffers¶

Memory reserved once at startup and reused.

Example: The FFT buffer is created before the main loop.

Privacy¶

A person's control over how information about them is collected and used.

Example: Students decide whether audio may leave the room.

A document describing how a device protects privacy and gets permission.

Example: A teacher reviews the plan before the device is deployed.

Probe Programs¶

Small programs that test one part of the hardware.

Example: A probe prints microphone levels.

Profiling¶

Measuring where a program spends its time or memory.

Example: Profiling shows that drawing takes more time than the FFT.

Project Due Date¶

The date a project must be handed in.

Example: DUE: History poster marks a due date.

Prompt Injection¶

Hidden instructions in text that trick an agent into unwanted actions.

Example: A calendar title says "ignore your rules."

A messaging style in which senders publish to topics and receivers subscribe to the topics they want.

Example: All classroom devices subscribe to one alert topic.

Publisher¶

An MQTT client that sends messages to a topic.

Example: The school server is the publisher of alerts.

Pull-Up Resistor¶

A resistor that holds an input at a high voltage until a switch pulls it low.

Example: An internal pull-up keeps a button pin high when unpressed.

Pure Python FFT¶

An FFT written only in ordinary Python code.

Example: It is easy to read but too slow for the frame budget.

Push Button¶

A switch that connects a circuit only while it is pressed.

Example: The Mode button is a push button wired to a GPIO pin.

Push-to-Talk¶

A mode in which the device listens only while a button is held or after it is pressed.

Example: Hold Mode to ask a question.

QoS Levels¶

MQTT settings that control how reliably a message is delivered.

Example: QoS 1 delivers at least once.

Raspberry Pi Pico 2 W¶

A low-cost microcontroller board with the RP2350 chip and a Wi-Fi radio.

Example: The Pico 2 W is the brain of the Open Study Buddy device.

Real-Time Constraint¶

A requirement that work finish within a fixed time.

Example: Audio must be processed as fast as it arrives.

Real-Valued Input¶

Input made of ordinary numbers, with no imaginary part, as audio samples are.

Example: Microphone samples are real-valued input to the FFT.

Recording an Utterance¶

Capturing the audio of one spoken request.

Example: The device records until the button is released.

Region Layout¶

A screen design divided into areas that update independently.

Example: Separate regions hold time, mascot, spectrum, message, and status.

Reminder¶

A notification sent before an event.

Example: The device reminds you the night before a test.

REPL¶

An interactive prompt that reads one Python statement, runs it, and prints the result.

Example: Typing 1 + 1 at the REPL prints 2.

Request-Reply Contract¶

The small, fixed message format that the device and server agree on, so either side can be replaced without changing the other.

Example: The device sends JSON with a text field and expects JSON with a reply field.

Request-Response Pattern¶

A messaging style in which a client asks and a server replies.

Example: HTTP uses request-response.

requests Library¶

A MicroPython library for making HTTP requests.

Example: requests.post(url, json=data) sends a question.

REST Endpoint¶

A web address that accepts requests for a specific action.

Example: /ask accepts questions.

Retained Message¶

A message the broker stores and gives to new subscribers.

Example: A new device immediately gets the latest test alert.

Retry and Backoff¶

Trying again after a failure while waiting longer between attempts.

Example: Retries occur after 1, 2, then 4 seconds.

RGB565 Color¶

A 16-bit color format with 5 bits of red, 6 of green, and 5 of blue.

Example: Pure red in RGB565 is 0xF800.

Ring Buffer¶

A fixed-size buffer in which new data overwrites the oldest when it reaches the end.

Example: A ring buffer holds the latest second of audio.

RMS Loudness¶

A measure of signal strength found from the square root of the average of squared samples.

Example: A louder room produces a higher RMS value.

Rolling Window¶

A moving span of the most recent data.

Example: The detector keeps the last second of features.

Room Acoustics¶

How a room's size and surfaces affect sound.

Example: Echoes in a gym raise the noise floor.

Round Color Display¶

A circular screen that shows full-color images and text, here 360 by 360 pixels.

Example: The round display shows the clock face and the school mascot.

Round Display Mask¶

A rule that skips pixels outside the circular visible area.

Example: Corner pixels of a square image are not drawn.

RP2350 Microcontroller¶

The chip on the Pico 2 that contains two processor cores, memory, and input/output hardware.

Example: The RP2350 runs MicroPython and the FFT code.

Rule-Based Agent¶

An agent that picks replies from fixed rules written by a programmer instead of generated by a language model.

Example: If the question contains "test," the agent reads the next TEST event.

Sample Rate¶

The number of samples taken each second.

Example: A 16,000 Hz sample rate gives 16,000 samples per second.

Sampling¶

Measuring a continuous signal at regular instants.

Example: The microphone is sampled thousands of times per second.

School Calendar¶

A schedule of school events, tests, and due dates.

Example: The calendar lists a science test on Friday.

School Mascot¶

A character that represents a school, shown on the device display.

Example: A griffin appears on the clock screen.

School Mascot Design¶

Preparing a mascot image for the round display.

Example: A simple design with strong colors reads well at small size.

School-Hosted Agent¶

An agent run by a school on its own equipment, under school rules for data and configuration.

Example: A school runs the agent on a Raspberry Pi in the library and connects it to the school calendar.

Secrets Management¶

Keeping passwords and tokens out of shared code and logs.

Example: Credentials live in a private config file.

Self-Hearing Problem¶

The device's microphone picking up its own speaker output.

Example: The agent mistakes its own spoken reply for a new question.

Self-Hosted Agent¶

An agent that runs on computers the user or school controls, so the owner chooses its settings and which data it may touch.

Example: A buddy server running on a school Raspberry Pi is self-hosted.

Self-Test Program¶

A program that checks every part and reports results.

Example: It tests the display, microphone, speaker, and buttons.

Serial Data Line¶

The I2S wire that carries the audio bits.

Example: The microphone puts samples on the serial data line.

Serial Debugging¶

Finding problems by printing messages over the USB serial connection.

Example: Print the RMS value to the REPL.

Server-Side Parsing¶

Processing data on the server rather than on the Pico.

Example: The server parses ICS files because the Pico has little memory.

Settings Screen¶

A display page where users change options such as volume.

Example: The settings screen lists volume and brightness.

Signal-to-Noise Ratio¶

The ratio of desired signal strength to background noise strength.

Example: A high ratio means speech stands out clearly.

Sine Table¶

A precomputed list of sine values used to build tones quickly.

Example: Tone code reads values from the table instead of computing each one.

Single-Speaker Limits¶

The loss of accuracy when someone other than the enrolled speaker says the phrase.

Example: A friend's voice may not match the template.

Sound Wave¶

A pressure variation traveling through air that the ear perceives as sound.

Example: A tone is a repeating sound wave.

Speaker¶

A device that turns an electrical signal into sound.

Example: The kit speaker plays tones and spoken answers.

Speaking Pace Sensitivity¶

A weakness in which detection changes when the wake phrase is spoken faster or slower.

Example: A slow "Hey Pico" scores lower than the enrolled one.

Spectral Leakage¶

Spread of a frequency's energy into neighboring bins.

Example: A pure tone shows energy in bins on both sides without a window.

Spectrogram¶

A display showing how the spectrum changes over time.

Example: Brighter colors mark stronger frequencies as time scrolls.

Spectrum Display¶

A screen graphic showing frequency strengths as bars.

Example: Twelve bars move with the sound of speech.

Speech Floor Gate¶

A threshold set above the noise floor that decides if sound might be speech.

Example: Audio below the gate is ignored.

Speech Level¶

The loudness of a person talking near the microphone.

Example: Speech level is measured while a student reads a sentence.

Speech-to-Text Service¶

A service that converts recorded speech into written text.

Example: The server transcribes the utterance before answering.

SPI Bus¶

A fast serial connection that uses a clock line and data lines to move data between a controller and a peripheral.

Example: The Pico sends pixel data to the display over SPI.

SPI Display Driver¶

Code that sends commands and pixel data to a display over SPI.

Example: The driver provides functions to set a window and write pixels.

Sprite¶

A small image that can be drawn and moved on the screen.

Example: A mascot sprite blinks on the display.

SRAM¶

Fast working memory that loses its contents when power is removed.

Example: Audio buffers live in SRAM while the program runs.

State Machine¶

A program structure with a fixed set of states and rules for moving between them.

Example: The device moves from clock to listening to thinking to speaking.

Status Indicator¶

A display element that shows the device's current condition.

Example: A red dot shows that the microphone is listening.

Stored Audio Playback¶

Playing sound from a saved file or buffer.

Example: A saved greeting plays when the device starts.

Streaming Audio¶

Sending audio continuously as it is captured.

Example: Samples flow to the server while the user is still speaking.

Student Privacy Law¶

Laws that protect information about students.

Example: A school consults its policies before deployment.

Study Timer Buddy¶

A buddy that times study sessions and responds to questions.

Example: It counts 25 minutes and announces a break.

Subscriber¶

An MQTT client that receives messages for topics it follows.

Example: Each device is a subscriber.

Swappable Brain¶

A design in which the software that produces answers can be exchanged for another without changing the device code.

Example: Replacing a rule-based server with an LLM-backed one while the Pico code stays the same.

System Integration¶

Combining separate features into one working device.

Example: The clock, audio, FFT, and agent run together.

Table Precomputation¶

Calculating values ahead of time and storing them for lookup.

Example: A sine table replaces repeated sine calculations.

Template Correlation¶

A similarity score between a stored template and incoming features.

Example: A higher correlation means the audio sounds more like the template.

Template Matching¶

Detecting a pattern by comparing input to a stored example.

Example: Live audio features are compared to the enrolled template.

TEST and DUE Prefixes¶

Title conventions that mark tests and due dates.

Example: TEST: Algebra and DUE: Essay.

Test Date Detection¶

Recognizing which events are tests.

Example: Titles starting with TEST: are tests.

Text Rendering¶

Drawing characters on the display as pixels.

Example: The agent's reply is rendered as text in the message region.

Text-to-Speech Service¶

A service that converts written text into spoken audio.

Example: The reply text becomes a WAV file for the speaker.

Thonny IDE¶

A beginner-friendly editor for writing, running, and saving MicroPython programs on a Pico.

Example: Click Run in Thonny to execute a script on the Pico.

Threat Model¶

A list of what could go wrong, who might cause it, and what is protected.

Example: It names classroom eavesdropping and stolen tokens.

Threshold Trade-Off¶

The balance in which lowering the threshold lowers false rejects but raises false accepts.

Example: A lower threshold wakes the device more often but also by accident.

Time Domain¶

A view of a signal as values over time.

Example: A waveform plot shows the time domain.

Time Zones¶

Regions that share a standard clock time.

Example: An event at 9:00 in one zone is a different hour in another.

Timeouts¶

Limits on how long to wait for a response.

Example: A five-second timeout ends a stalled request.

Timer¶

A hardware counter that triggers actions at regular intervals.

Example: A timer fires every 50 ms to check the buttons.

Timing Verification¶

Measuring that code finishes within its allowed time.

Example: The FFT must finish in under 32 ms.

TLS Encryption¶

A method that scrambles network data so others cannot read it.

Example: TLS protects a password in transit.

Tone Generation¶

Creating samples that produce a pure sound at a chosen frequency.

Example: The device plays a 1,000 Hz beep.

Topic¶

A named channel used to route MQTT messages.

Example: school/room12/alerts

Topic Naming Scheme¶

A consistent pattern for naming topics.

Example: school/classroom/device/status

Topic Wildcards¶

Symbols that let a subscription match several topics.

Example: school/+/alerts matches every classroom.

Trained Keyword Spotting¶

Detecting words using a model trained on many recordings.

Example: A neural network trained on thousands of voices recognizes "Hey Pico."

Transcript Handling¶

Rules for storing, sharing, and deleting text of what was said.

Example: Transcripts are kept only on the school server.

Twiddle Factors¶

Precomputed sine and cosine constants used by the FFT.

Example: A table of twiddle factors avoids recalculating trigonometry.

Typed Arrays¶

Arrays whose elements all share one fixed number type.

Example: array('h') stores 16-bit signed integers.

umqtt Library¶

The MicroPython library for MQTT clients.

Example: umqtt.simple connects the Pico to a broker.

Unit Normalization¶

Scaling a vector so its length equals one.

Example: Normalized templates give scores between -1 and 1.

Up Button¶

The button that raises a value or moves up in a menu.

Example: Up increases the speaker volume.

Upcoming Events Query¶

A request for events within a coming time span.

Example: "What is due this week?"

Update Bandwidth¶

The amount of data per second that can be sent to the display.

Example: Low update bandwidth limits how often a full frame can be redrawn.

USB Power¶

Electrical power supplied through a USB cable.

Example: A phone charger supplies USB power to the device.

User Feedback¶

Visible or audible responses that tell the user what the device is doing.

Example: A beep confirms the wake phrase was heard.

User Testing¶

Observing real users to learn what works and what confuses them.

Example: Classmates try the button scheme and report problems.

Utterance Boundaries¶

The start and end points of a spoken phrase within audio.

Example: Silence marks the end of the utterance.

Viper Code¶

MicroPython code compiled with the @micropython.viper decorator for faster integer and pointer operations.

Example: A viper inner loop runs several times faster than plain Python.

Voice Activity Detection¶

Deciding whether an audio frame contains speech.

Example: The device stops recording after the voice activity detection reports silence.

Voice and Prompts¶

The speech style and spoken messages the device uses.

Example: A cheerful greeting each morning.

Volume Control¶

Adjusting how loud the speaker output is.

Example: Up and Down change volume in steps.

Volume Meter¶

A display element that shows how loud the sound is.

Example: A bar fills as RMS loudness rises.

Wake Confirmation Beep¶

A short sound that signals the device heard the wake word.

Example: A rising two-tone beep plays after detection.

Wake Cooldown¶

A short delay after a detection during which new detections are ignored.

Example: A two-second cooldown prevents repeated triggers.

Wake Word¶

A spoken phrase that signals the device to start listening.

Example: "Hey Pico" starts a request.

Wake-Word Enrollment¶

Recording samples of the wake phrase to build a detection template.

Example: The student says "Hey Pico" five times during enrollment.

WAV File Format¶

A common audio file format that stores raw samples with a header.

Example: A recorded utterance is saved as a WAV file.

WebSocket¶

A persistent two-way network connection between client and server.

Example: Always-on mode streams audio over a WebSocket.

Wi-Fi Connection¶

A wireless link between the device and a local network.

Example: The Pico joins the classroom network with a name and password.

Wi-Fi Radio¶

The wireless hardware that connects the Pico 2 W to a local network.

Example: The Wi-Fi radio lets the device reach the buddy server.

Window Fill Percentage¶

How much of the rolling window has been filled with data.

Example: Scoring begins when the window is fully filled.

Windowing¶

Multiplying a frame by a smooth shape that tapers its edges before the FFT.

Example: A window reduces leakage from abrupt frame edges.

Wiring Verification¶

Confirming that each part is connected to the correct pins.

Example: Compare wires to the pin assignment table.

Word Select¶

The I2S signal that marks the start of each sample and which channel it belongs to.

Example: Word select toggles between left and right channels.