Connecting Raspberry Pi to the flight controller

In order to program autonomous flights, work with Pixhawk or Pixracer over Wi-Fi, use controller app and access other functions you need to connect your Raspberry Pi to the flight controller.

USB connection

USB connection is the preferred way to connect to the flight controller.

1. Connect your FCU to the Raspberry Pi using a microUSB to USB cable.
2. Connect to the Raspberry Pi over SSH.

3. Make sure that the connection is working properly by running the following command on the Raspberry Pi:

    rostopic echo /mavros/state
   

   The connected field should have the True value.

You need to set the CBRK_USB_CHK parameter to 197848 for the USB connection to work.

UART connection

UART connection is another way for the Raspberry Pi and FCU to communicate.

If the pin marked GND is occupied, you can use any other ground pin (look at the pinout for reference).

1. Connect the TELEM 2 port on the flight controller using a UART cable to the Raspberry Pi pins following this instruction: the black cable (GND) to Ground, the green cable (UART_RX) to GPIO14, the yellow cable (UART_TX) to GPIO15. Do not connect the red cable (5V).
2. In PX4 of version v1.9.0 or higher, set parameter values: MAV_1_CONFIG to TELEM 2, SER_TEL2_BAUND to 921600 8N1. In PX4 of version prior to v1.9.0 the parameter SYS_COMPANION should be set to Companion Link (921600 baud, 8N1), to set it correctly use the old version of QGC v3.3.1.
3. Connect to the Raspberry Pi over SSH.

4. Check the presence of the parameters enable_uart=1 and dtoverlay=pi 3-disable-bt in the file /boot/config.txt by running the following command on the Raspberry Pi:

    cat /boot/config.txt | grep -E "^enable_uart=.|^dtoverlay=pi3-disable-bt"
   

   If the parameters in the file are different or missing, then edit the file and restart the Raspberry Pi.

5. Change the connection type from usb to uart in the Clover' launch file ~/catkin_ws/src/clover/clover/launch/clover.launch:

    <arg name="fcu_conn" default="uart"/>
   

   If you change the launch file, you need to restart the `clover' service:

    sudo systemctl restart clover
   

6. Make sure that the connection is working properly by running the following command:

    rostopic echo -n1 /mavros/state
   

   The connected field should have the True value.

Read more in the PX4 docs: https://docs.px4.io/main/en/peripherals/serial_configuration.html.

Next: Using QGroundControl over Wi-Fi