PicoRobot

PicoRobot is a Rust-based project for the Pololu 3pi+ 2040 Robot, utilizing the rp-pico HAL and the RTIC framework.

Prerequisites

Before you begin, ensure you have the following installed:

1. Rust: Install via rustup.rs.
2. Thumbv6m Target:

   rustup target add thumbv6m-none-eabi

3. probe-rs: For flashing and debugging.

   cargo install probe-rs --features cli

Configuration

Ensure that .cargo/config.toml is configured for your debug probe. The default configuration uses probe-rs.

[runner]
runner = "probe-rs run --chip RP2040 --protocol swd"

Running Examples

To flash and run a specific example from the examples/ directory, use the --example flag:

cargo run --release --example <example_name>

Available Examples

Example	Description
motors_demo	Basic motor control (forward, backward, stop)
encoders_demo	Reading wheel encoders via PIO (Software Decoding)
encoders_hw_demo	High-performance asynchronous encoder tracking (Hardware Decoding)
target_velocity_demo	PID-controlled constant velocity using encoder feedback
line_sensors_demo	Calibrating and reading the 5-channel reflectance sensor array
line_following_demo	Full line-following application with calibration and PID steering
leds_demo	Controlling the RGB LEDs
leds_off	Utility to turn off all RGB LEDs
display_demo	Using the OLED display with embedded-graphics
imu_demo	Reading data from the onboard IMU
uart_echo_demo	Echoes characters received on UART0 (GP28/GP29)
blink_led	Basic blinky example (migrated from main)

Testing UART Echo

To test the uart_echo_demo, you will need a USB-to-TTL serial adapter connected to the robot's UART pins (GP28/TX and GP29/RX).

1. Connect the Adapter:
   • Adapter RX -> Robot GP28 (TX)
   • Adapter TX -> Robot GP29 (RX)
   • Adapter GND -> Robot GND
2. Flash the Demo:

   cargo run --release --example uart_echo_demo

3. Connect using screen: Identify your serial device (e.g., /dev/tty.usbserial-XYZ) and run:

   screen /dev/tty.<your_serial_device> 115200

   To exit screen, press Ctrl+A then K then Y.

Hardware Modules

The project provides high-level drivers for the robot's subsystems in src/hal/.

Module	Description	Key Features
motors	Dual DC Motor Control	PWM speed control, Direction handling
encoders	Quadrature Encoders	PIO-based hardware counting, Zero CPU overhead
closed_loop_motors	Velocity Control	PID controller integration for constant speed
line_sensors	Reflectance Array	5-channel RC timing, Calibration, Scaled output
display	OLED Screen	SH1106 driver, embedded-graphics integration
leds	RGB LEDs	APA102 (DotStar) driver via SPI
imu	Inertial Sensors	Accelerometer and Gyroscope access

Logging

This project uses defmt for efficient logging. When running with probe-rs, logs are automatically displayed in your terminal.

Log Levels

You can set the log level at runtime by setting the DEFMT_LOG environment variable:

DEFMT_LOG=trace cargo run --release --example target_velocity_demo

Available levels: error, warn, info, debug, trace.

Macros

Use these macros in your code to print logs:

• error!("Error message")
• warn!("Warning message")
• info!("Info message")
• debug!("Debug message")
• trace!("Trace message")