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stephendade / mav_rp2040

MAVLink for the RP2040
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ardupilot mavlink micropython raspberry-pi-pico rp2040

readme

MAVLink Sensor for the RP2040

This repository contains code for automatically sending analogue sensed values from a RP2040-based board (such as a Raspberry Pi Pico board) to a flight controller via MAVLink.

This allows the sensed values to appear in the GCS.

Examples are given in both Python and C.

Hardware setup

Setup:

  1. Connect the RP2040 to a spare UART on the flight controller. Only the +5V, RX, TX and GND lines need to be connected
  2. Connect any desired sensors to the A0, A1, A2 and A3 ports on the RP2040
  3. Ensure the UART on the flight controller is set to MAVLink2, 57600 baud

C

The Raspberry Pi Pico SDK is required to be installed.

NOTE: ArduPilot and the RP2040 require different versions of the arm-gcc compiler. Please be careful about which compiler is on the system path. THe RP2040 will typically use the compiler at /usr/bin, whilst ArduPilot will typically use the compiler at /opt/gcc-arm-none-eabi-10-2020-q4-major/bin

Use to following commands to build the program:

mkdir ./c/build
cd ./c/build
cmake .. -DPICO_BOARD=pico -DPICO_TOOLCHAIN_PATH=/usr/bin/
make

Then copy the ./c/build/mavlink_periph.uf2 file to the RP2040.

Python

The Micropython framework is required to be installed on the RP2040, in order to run the code.

Use the upload.py script to upload the code to the RP2040.

Running

The code will automatically run on boot, flashing a LED each time a MAVLink heartbeat packet is received.

The RP2040 will send readings from the analogue ports A0, A1, A2 and A3 at 1 second intervals. The readings are in volts.

The readings can be viewed at a GCS, such as Mission Planner or MAVProxy.

In MAVProxy, use the following command:

graph NAMED_VALUE_FLOAT[ADC0].value NAMED_VALUE_FLOAT[ADC1].value NAMED_VALUE_FLOAT[ADC2].value NAMED_VALUE_FLOAT[ADC3].value

In Mission Planner, select the "peripheral" component, then right click in the "quick" tab and select the ADC value to display:

Developers

Due to resource constraints in Micropython, a limited MAVLink interpreter is included (pymavminimal.py and mavcrc.py). Message signing is not available. See main.py for a basic example of sending and receiving MAVLink messages.

The follow messages are supported:

AHRS (163)
DATA16 (169)
DATA32 (170)
DATA64 (171)
DATA96 (172)
HEARTBEAT (0)
SYS_STATUS (1)
SYSTEM_TIME (2)
GPS_RAW_INT (24)
ATTITUDE (30)
VFR_HUD (74)
COMMAND_INT (75)
COMMAND_LONG (76)
COMMAND_ACK (77)
NAMED_VALUE_FLOAT (251)
NAMED_VALUE_INT (252)
STATUSTEXT (253)
SCALED_IMU (26)