Communicating with Raspberry Pi via MAVLink
This page explains how to connect and configure a Raspberry Pi (RPi) so
that it is able to communicate with a flight controller using
the MAVLink protocol over a serial connection. This can be used to
perform additional tasks such as image recognition which simply cannot
be done by the flight controller due to the memory requirements for storing
Connecting the Flight controller and RPi Hardware
Connect the flight controller’s TELEM2 port to the RPi’s Ground, TX and RX pins as
shown in the image above. More details on the individual RPi’s pin
functions can be found
The RPi can be powered by connecting +5V source to the +5V pin or from USB in.
Addon boards such as the Pi-Connect
can simplify the connection of the RPi by providing a power supply and telemetry port.
Depending on the model of RPi used and internal/external peripherals used, +5V power requirements can vary from 80mA to close to 2.5A. The power budget for the particular system configuration should be assessed to determine the requirements for the +5V supply current. It is usually not recommended that +5v be supplied via the flight controller’s TELEM port connector.
Setting up the flight controller
Connect to the flight controller with a ground station (i.e. Mission Planner) and set the following parameters:
- SERIAL2_PROTOCOL = 2 (the default) to enable MAVLink 2 on the serial port.
- SERIAL2_BAUD = 921 so the flight controller can communicate with the RPi at 921600 baud.
- LOG_BACKEND_TYPE = 3 if you are using APSync to stream the dataflash log files to the RPi
Configure the serial port (UART)
If not already configured, the Raspberry Pi’s serial port (UART)
will need to be enabled. Use the Raspberry Pi configuration utility for this.
And in the utility, select “Interfacing Options”:
And then “Serial”:
When prompted, select
no to “Would you like a login shell to be accessible over serial?”.
When prompted, select
yes to “Would you like the serial port hardware to be enabled?”.
Reboot the Raspberry Pi when you are done.
The Raspberry Pi’s serial port will now be usable on
Configure the Wifi
If desired, the Raspberry Pi’s Wifi can be configured to create a
Wifi access point. This will allow other clients to connect to
the RPi and stream telemetry. See the official RPi documentation
The built-in Wifi on the Raspberry Pi does not have a large range. If range is an
issue, consider a USB Wifi adapter with external antenna.
Setup the RPi Software
There are a few different software options for communicating with the flight controller. All use the MAVLink
protocol for communication.
The easiest way to setup the RPi is to flash one of the existing APSync images:
Purchase a formatted 8GB or 16GB SD card (16GB is better because some 8GB cards will not be quite large enough to fit the image) and insert into your laptop/desktop computer’s SD card slot
Download the latest image from firmware.ardupilot.org. Look for the file starting with “apsync-rpi”.
Use the Etcher software to load the image onto the micro SD card.
Insert the micro SD card into into the Pi’s micro SD card slot
There is a more recent APSync build for the RPi in the forums.
The APSync image will have the serial port (UART) already enabled.
MAVProxy can be used to send commands to the flight controller from the Pi.
It can also be used to route telemetry to other network endpoints.
This assumes you have a SSH connection to the Pi. If not, see see the
the RPi Documentation.
See the MAVProxy Documentation for install instructions
To test the RPi and flight controller are able to communicate with each other
first ensure the RPi and flight controller are powered, then in a console on the
python3 mavproxy.py --master=/dev/serial0 --baudrate 921600 --aircraft MyCopter
Once MAVProxy has started you should be able to type in the following
command to display the
ARMING_CHECK parameters value
param show ARMING_CHECK
param set ARMING_CHECK 0
If you get an error about not being able to find log files or if
this example otherwise doesn’t run properly, make sure that you haven’t
accidentally assigned these files to another username, such as
Mavlink-router is used to route telemetry between the RPi’s serial port
and any network endpoints. See the documentation
for install and running instructions.
After installing, edit the mavlink-router config file’s
UART section to:
Device = /dev/serial0
Baud = 921600
You will also need to add an additional UDP endpoint allow other ground stations on the same
network to connect to the Pi. Edit the mavlink-router config file
Mode = eavesdropping
Address = 0.0.0.0
Port = 14550
PortLock = 0
The most up-to-date instructions for Installing DroneKit on Linux are in the DroneKit-Python documentation.
a web-based GUI for configuring flight controller telemetry, logging,
video streaming and network configuration.
Installation is via a disk image:
- Purchase a formatted 8GB (or larger) micro SD card and insert into your laptop/desktop computer’s SD card slot
- Download the latest image.
- Use the Etcher software to load the image onto the micro SD card.
- Insert the micro SD card into into the Pi’s micro SD card slot
The Rpanion-server image will have the serial port (UART) already enabled.
Connecting with the Mission Planner
The flight controller will respond to MAVLink commands received through Telemetry
1 and Telemetry 2 ports (see image at top of this page) meaning that
both the RPi and the regular ground station (i.e. Mission planner, etc)
can be connected. In addition it is possible to connect the Mission
Planner to the MAVProxy application running on the RPi similar to how it is done for SITL.
Primarily this means adding an
--out <ipaddress>:14550 to the
MAVProxy startup command with the being the address of the PC running
the mission planner. On windows the
ipconfig can be used to
determine that IP address. On the computer used to write this wiki page
the MAVProxy command became:
mavproxy.py --master=/dev/ttyAMA0 --baudrate 57600 --out 192.168.137.1:14550 --aircraft MyCopter
Connecting with the mission planner is shown below: