List of Hands-On Lab Ideas

This is the idea list for the Labs section. Nothing here is written yet. Each row is a candidate lab, kept to one line so we can sort, cut, and reorder before spending any writing effort. Once a lab is chosen it gets its own page under docs/labs/<lab-id>/index.md.

Why labs come before the big arm

A $330 arm is a poor place to learn that a servo needs its own power supply. A $4 servo on a breadboard is a great one. Every lab here is cheap, small, and safe to get wrong.

Design Assumptions

These assumptions shape every idea below. Change one and the list changes.

Assumption	Choice
Microcontroller	Raspberry Pi Pico 2 W (a plain Pico also works for every lab except the Wi-Fi ones)
Language	MicroPython, edited in Thonny; mpremote introduced once labs get larger
Station	One Pico, one breadboard, one OLED, one ToF sensor, one USB cable per student or pair
Budget	About $60 per station for the core kit (less when pairs share a multimeter), about $170 with every add-on (estimates; verify prices before publishing)
Prior skill	Python from Learning Python. MicroPython and electronics are taught just in time
Bridge to the book	Labs that touch the laptop use the same pyserial and Python style as Chapters 4, 10, and 11

Pico pins are not motor power

A Pico GPIO pin can supply a few milliamps. A hobby servo can pull an amp when it stalls. Every servo and stepper lab must power the motor from a separate supply with a shared ground.

How to Read the Tables

• ID is track letter + number. It becomes the lab's directory name.
• Min is the estimated classroom time, including wiring.
• Level: 1 first lab with that part, 2 builds on a level 1 lab, 3 stretch or instructor-led.
• Source shows where an existing lesson can be adapted:
  • LM = the Learning MicroPython book at learning-micropython/docs/
  • SR = the STEM Robots book at stem-robots/docs/
  • New = nothing to borrow; we write it from scratch
• Ch is the chapter in this book that the lab reinforces.

Track A: Getting Started with the Pico

Short labs that every other track assumes. Skip any that students already know.

ID	Lab	What students build and learn	Min	Level	Source	Ch
A1	Hello, Pico	Flash MicroPython, open Thonny, blink the LED, use the REPL	30	1	LM basics/01-blink.md, SR setup/05-thonny-installation.md	1
A2	Buttons and Debouncing	Read a push button with pull-ups; see contact bounce and fix it in software	30	1	LM basics/03-button.md, advanced-labs/21-button-callback.md	1
A3	Multimeter and Ohm's Law	Measure voltage and resistance, then predict a current before measuring it	40	1	LM hands-on-labs/05-electronics-fundamentals/breadboards.md	3
A4	Reading a Knob	Use the ADC to read a potentiometer and print values; map 0-65535 to an angle	30	1	LM basics/03-potentiometer.md	5
A5	Hello, OLED	Wire an SSD1306 over I2C, write text, run an I2C scanner	40	1	LM hands-on-labs/15-oled-setup/11-oled-ssd1306-i2c.md, advanced-labs/06-i2c.md	4
A6	Config Files and Pin Maps	Keep pin numbers and calibration in config.json so code never hard-codes a pin	30	2	SR lessons/07-config-file.md	1

Track B: Hobby Servos

The core of the book's first half. Five of these should be written first.

ID	Lab	What students build and learn	Min	Level	Source	Ch
B1	First Servo Sweep	PWM at 50 Hz; convert an angle to a pulse width; sweep 0 to 180 degrees	40	1	LM basics/04-servo.md, hands-on-labs/12-motors-servos-steppers/06-servos.md	5
B2	Calibrate Your Servo	Find the true minimum and maximum pulse for this servo and save them to config.json; compare an SG90 and an MG90S	40	2	New	5
B3	Knob-Controlled Servo	Potentiometer sets the angle; OLED shows the angle and the pulse width	40	2	LM hands-on-labs/12-motors-servos-steppers/10-tof-motor-pot-display.md	5
B4	Smooth Motion	Limit speed with a step-per-tick ramp, then add easing at the ends; compare to a jump	45	2	New	11
B5	Servo Power and Brownouts	Run a servo from USB, watch the Pico reset under load, then fix it with a separate 5 V supply and a shared ground	45	2	New	3
B6	Servo Under Load	Hang weights on a horn-mounted arm and measure current with an INA219; find the stall current	60	3	New	5
B7	Pan-Tilt Drawing	Two servos and a laser pointer or pen trace squares, circles, and Lissajous curves	50	2	New	11
B8	Gripper with a Limit	Open and close a gripper; stop when current jumps because it holds an object	60	3	New	11
B9	Three-Pot Leader, Three-Servo Follower	Three knobs are the leader arm; three servos copy them. A tiny leader-follower pair	60	3	New	2, 11
B10	Hack a Servo for Feedback	Tap the potentiometer wiper inside an SG90 and read the real joint angle on an ADC pin	60	3	New	5

Track C: Sensors and Displays

Sensors tell the arm about the world and about itself.

ID	Lab	What students build and learn	Min	Level	Source	Ch
C1	Ultrasonic Ranging	HC-SR04 echo timing; convert microseconds to centimeters; why 5 V echo needs a divider	45	1	LM sensors/03-ping.md, SR lessons/55-ultrasonic-sensors.md	5
C2	Time-of-Flight Distance	VL53L0X over I2C; read millimeters; show on the OLED	45	1	LM sensors/07-VL53L0X_GY.md, SR lessons/50-tof-sensors.md	5
C3	Noise and Filtering	Log 500 readings, plot in Thonny, then compare a moving average with a median filter	45	2	New	5
C4	Rotary Encoder	Count quadrature pulses with interrupts; show position and direction	50	2	LM sensors/10-rotary-encoder.md	5
C5	Tilt Angle from an IMU	MPU6050 gives a link angle; smooth it with a complementary filter	60	3	LM chapters/10-motion-light-sensors, SR kits/imu-mpu6050	5, 12
C6	Limit Switches and Homing	Wire a microswitch; drive a joint until it clicks, then call that angle zero	45	2	New	8
C7	Current and Voltage Monitor	INA219 on the supply line; print volts, amps, and watts on the OLED	45	2	New	3
C8	Magnetic Angle Sensor	AS5600 absolute encoder on a shaft; read 12-bit angle over I2C	50	3	New	5
C9	Live Plot on the Laptop	Stream sensor values from the Pico over USB serial; plot them with Python on the laptop	50	2	New	4

Track D: DC Motors and Steppers

Servos hide the control loop. These labs open it up.

ID	Lab	What students build and learn	Min	Level	Source	Ch
D1	DC Motor with an H-Bridge	DRV8833 forward, reverse, and brake; pair with the H-Bridge Current Paths MicroSim	50	1	LM hands-on-labs/12-motors-servos-steppers/03-h-bridge.md, 08-drv8833.md; docs/sims/h-bridge-current-paths/	5
D2	Motor Speed and RPM	PWM duty vs. speed; measure RPM with an encoder or a slotted wheel	50	2	SR lessons/20-motor-speed.md, 25-pwm.md	5
D3	Stepper Basics with a 28BYJ-48	ULN2003 driver; full-step and half-step sequences; count steps per revolution	50	1	LM hands-on-labs/12-motors-servos-steppers/07-stepper-motors.md	5
D4	NEMA 17 with Step/Dir	A4988 or DRV8825 driver; set the current limit with a multimeter; microstepping	60	2	New	5
D5	Acceleration Ramps and Lost Steps	Start too fast and watch the motor stall; add a ramp and fix it	50	2	New	5
D6	Turntable with Homing	Stepper plus limit switch; command angles in degrees, not steps	60	3	New	8, 11
D7	Closed-Loop Stepper	AS5600 on the stepper shaft detects a missed step and corrects it	60	3	New	5
D8	PID Position Control	DC motor plus encoder; tune P, then I, then D, and plot each response	70	3	New	5

Track E: Build a Mini Arm

These labs turn parts into a mechanism. They need a cheap arm: laser-cut or printed links, two to four MG90S servos, and a pen or pointer for the end.

ID	Lab	What students build and learn	Min	Level	Source	Ch
E1	Assemble a 2-Link Arm	Mount two servos, set horns at known angles, label shoulder and elbow	60	2	New; see robot-arm-drawing skill and docs/sims/two-link-workspace-explorer/	2
E2	Forward Kinematics on the Pico	Given two angles, compute the hand position; check it against a ruler	60	3	New	12
E3	Inverse Kinematics Pen Plotter	Given a target point, compute the angles; draw a line, a square, and a circle	90	3	New	12
E4	Workspace Mapping	Sweep every angle pair; mark reachable points on graph paper; compare to the Two-Link Workspace MicroSim	60	2	New	2, 12
E5	Joystick Teleoperation	Dual-axis joystick drives two joints; add a button to open and close the gripper	50	2	LM misc/projects.md (joystick notes)	11
E6	Waypoint Recorder	A button saves the current pose to a list; a second button plays the list back and stores it in a JSON file	60	3	LM advanced-labs/17-file-system.md	11
E7	Pan-Tilt Depth Map	Two servos sweep a ToF sensor; build a 2D depth map	70	3	LM hands-on-labs/12-motors-servos-steppers/09-2d-depth-mapping.md	14
E8	Pick and Place a Block	Move above a block, descend, grip, lift, move, release; add pauses and speed limits	90	3	New	11, 18

Track F: Communication and Bus Servos

This track connects the Pico to the protocol chapters. It is the bridge from hobby servos to the STS3215 servos in the SO-ARM101.

ID	Lab	What students build and learn	Min	Level	Source	Ch
F1	UART Loopback	Wire TX to RX on one Pico; send bytes and read them back; see baud-rate mismatch	40	1	New	4
F2	Two Picos Talking	Pico A sends a packet; Pico B verifies the checksum and answers	60	2	New	4
F3	Pico as a Serial Arm Controller	Laptop Python sends MOVE 1 90; the Pico moves a servo. First hardware abstraction layer	60	2	New	4, 10
F4	Fake Arm, Real Arm	Same laptop program drives a software fake arm and the Pico arm through one class	50	3	New	10
F5	Logic Analyzer Lab	Capture PWM and UART with an inexpensive logic analyzer (or a second Pico); read the waveforms	60	2	New	4
F6	Ping an STS3215	Half-duplex UART to one bus servo; build the ping packet by hand; read position, voltage, and temperature	70	3	New	4, 5
F7	Move and Chain Bus Servos	Set servo IDs; move two servos on one wire; read all registers	70	3	New	4, 5
F8	CAN Loopback with an MCP2515	SPI CAN module in loopback mode; send and receive a frame; read arbitration IDs	70	3	New	4
F9	Two-Node CAN	Two Picos with MCP2515 modules exchange frames; add termination and see why it matters	70	3	New	4

Track G: Power and Safety

Safety labs are the ones students remember. They also match Chapters 3 and 17.

ID	Lab	What students build and learn	Min	Level	Source	Ch
G1	Power Budget	Measure idle, moving, and stall current for each motor; size a supply with a 50% margin	50	2	New	3
G2	Build an E-Stop	Normally closed button in series with a relay or MOSFET cuts motor power; Pico reads its state and shows it on the OLED	60	2	New	3, 17
G3	Soft Limits	A Joint class clamps angle and speed; test it with out-of-range commands	45	2	New	5, 17
G4	Heartbeat and Watchdog	Laptop sends a heartbeat; the Pico stops the arm if it goes quiet, and the hardware watchdog resets a hung program	60	3	LM advanced-labs/13-timers.md (WDT)	17
G5	Overheat and Overload Guard	Read temperature or load and stop the joint when it passes a threshold	50	3	New	5, 17
G6	Fuse and Wire Gauge	Compare thin and thick wire under load; measure voltage drop; blow a fuse on purpose in a safe setup	50	2	New; see docs/sims/wire-voltage-drop-explorer/	3

Track H: Integration and Capstones

Each capstone combines three or more earlier labs. Prerequisites are listed.

ID	Lab	What students build and learn	Min	Level	Prereqs	Ch
H1	Guarded Move	The gripper approaches an object and stops 2 cm away, using a ToF sensor	60	3	C2, E1, G3	14
H2	Servo Radar	A servo sweeps an ultrasonic or ToF sensor; draw a polar plot on the laptop	70	3	C2, B1, C9	14
H3	Teach Pendant	OLED, three knobs, and buttons on a handheld box that drives the mini arm and shows pose and status	90	3	A5, B3, E6, G2	11
H4	Distance-Triggered Wave	Wave the arm when a hand comes within 30 cm; add a cooldown so it never chatters	45	2	C2, B4	18
H5	Agent-Safe Tool Server	The Pico exposes move_to, read_distance, and stop over serial; a laptop script (later, an AI agent) calls them through a safety layer that enforces limits	120	3	F3, G3, G4	15, 16, 17
H6	Mini Leader-Follower Over Serial	Two Picos: one reads three knobs, one drives three servos, linked by UART with a heartbeat	120	3	B9, F2, G4	2, 11
H7	Draw a Signature	Record a pen path with the waypoint recorder, then replay it with IK smoothing	120	3	E3, E6	12

Suggested First Twelve to Write

Write these first. They form one connected path and each uses only parts we already plan to buy.

1. A1 Hello, Pico
2. A4 Reading a Knob
3. B1 First Servo Sweep
4. B2 Calibrate Your Servo
5. B5 Servo Power and Brownouts
6. B3 Knob-Controlled Servo
7. C2 Time-of-Flight Distance
8. B4 Smooth Motion
9. F3 Pico as a Serial Arm Controller
10. G3 Soft Limits
11. D3 Stepper Basics with a 28BYJ-48
12. B9 Three-Pot Leader, Three-Servo Follower

Core Station Kit (draft)

All prices are rough estimates for planning, not quotes.

Part	Qty	Approx. cost	Used by
Raspberry Pi Pico 2 W with headers	1	$7	All
Half-size breadboard and jumper kit	1	$6	All
SSD1306 128x64 I2C OLED	1	$5	A5 and later
VL53L0X ToF sensor	1	$4	C2, E7, H1, H2
HC-SR04 ultrasonic sensor and 2 resistors	1	$3	C1
10 kohm potentiometers	3	$2	A4, B3, B9
Push buttons	4	$1	A2, E6
MG90S micro servos	4	$12	B, E
5 V 3 A bench or wall supply with barrel jack adapter	1	$8	B5, G1
INA219 current sensor	1	$3	B6, C7, G1
Multimeter	1 per pair	$12	A3, G1
Core total		about $63 (about $51 without the multimeter)

Add-ons by track

Add-on	Approx. cost	Needed for
28BYJ-48 stepper with ULN2003 board	$4	D3
NEMA 17 stepper, A4988 or DRV8825 driver, 12 V supply	$25	D4-D7
AS5600 magnetic encoder board	$4	C8, D7
MPU6050 IMU	$3	C5
Rotary encoder module	$2	C4
DRV8833 board and small DC gear motor	$6	D1, D2, D8
Dual-axis analog joystick	$2	E5
Relay or logic-level MOSFET module, plus mushroom E-stop	$8	G2
MCP2515 CAN module (two) with 120-ohm terminators	$10	F8, F9
Bus-servo adapter and one STS3215 servo	$30	F6, F7
Cheap logic analyzer (24 MHz, 8 channel)	$10	F5
Mini arm links, laser cut or printed	$5	E1-E8

Dependency Chains

Read each line left to right. A lab needs the ones before it on its line.

Goal	Chain
Move a servo precisely	A1, A4, B1, B2, B3, B4
Build and aim a mini arm	B2, E1, E2, E3
Sense the world	A1, A5, C2, then H1 or H2
Control from a laptop	B1, F3, G3, F4, H5
Bus servos and CAN	F1, F2, F6, F7 (and F8, F9 for CAN)
Leader and follower	B3, B9, F2, G4, H6

MicroSim Ideas to Pair with Labs

A lab asks students to do; a MicroSim lets them predict first. These pair well and several already exist.

MicroSim	Pairs with	Status
H-Bridge Current Paths	D1	Exists (docs/sims/h-bridge-current-paths/)
Two-Link Workspace Explorer	E1, E4	Exists
Leader and Follower Mirror	B9, H6	Exists
Common Ground Loop	B5	Exists
Wire Voltage-Drop Explorer	G6	Exists
Servo Pulse-Width Explorer (adapt learning-micropython/docs/sims/servo-pwm-explorer/)	B1, B2	To build
Stepper Step Sequence Animator	D3, D4	To build
Debounce Waveform Viewer	A2	To build
Ultrasonic Echo Timing (adapt learning-micropython/docs/sims/ultrasonic-ranging/)	C1	To build
Acceleration Ramp Plotter	B4, D5	To build
UART Byte Timing Diagram	F1, F2	To build

Lab Page Template (proposal)

Every finished lab should follow the same shape so students learn where to look:

1. Goal in one sentence, and the one new idea (the book's one-new-idea rule)
2. Time, level, cost
3. Parts list with a link to the station kit
4. Safety check (power source, pinch points, what to unplug first)
5. Wiring diagram and a wiring table
6. Predict first: a question to answer before running anything
7. Code in short steps, each Python block with linenums="1"
8. What you should see, including the common wrong result
9. Troubleshooting table: symptom, likely cause, fix
10. Extend it: two stretch tasks
11. Check yourself: three short questions
12. Link to the chapter and to the next lab

Open Questions for the Author

1. Which Pico? Pico 2 W is assumed. A plain Pico is $4 cheaper and runs everything here except Wi-Fi.
2. Which mini arm? Laser-cut MG90S arm, printed arm, or a purchased $25 kit? E labs depend on this choice.
3. STS3215 from a Pico. The bus servo uses half-duplex TTL serial at high baud rates. Before writing F6 and F7, confirm a Pico plus an adapter board can drive it reliably; if not, run these labs from the laptop instead.
4. CAN. The Pico has no CAN controller, so F8 and F9 need the MCP2515 module. They are the most expensive and least reusable labs. Keep or cut?
5. Lab numbering. Keep track letters (A to H) or number labs in one global order like a course?
6. Where do answers go? Instructor guides are a separate section in this book and do not use the mascot.