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Version: 2.0 (Legacy)

Telemetry and OSD

warning

With Ardupilot you may need to enable certain "stream rate" parameters on the flight controller. More information is available on the rc with mavlink page

1. configure general OSD and telemetry parameters in openhd-settings-1.txt (both on AirPi and GroundPi)​

  • Set the Pi's serial port baudrate to the same baudrate as the serial telemetry data stream coming from the flight control. E.g. FC_TELEMETRY_BAUDRATE=57600 if your flightcontrol sends it's telemetry data using 57600 baud.
  • For the onboard Pi serial port leave default FC_TELEMETRY_SERIALPORT=/dev/serial0, if using an external USB2Serial adapter, set FC_TELEMETRY_SERIALPORT=/dev/ttyUSB0
  • If you want to connect your flight controller to the AirPi and use wifibroadcast for telemetry transmission, leave TELEMETRY_TRANSMISSION=wbc
  • If you have some other means of transmitting the telemetry to the ground (e.g. an LRS with serial downlink or 3DR dongles) choose TELEMETRY_TRANSMISSION=external to receive the telemetry stream on the ground Pi serial port. If using external telemetry transmission, also configure EXTERNAL_TELEMETRY_SERIALPORT_GROUND= and EXTERNAL_TELEMETRY_SERIALPORT_GROUND_BAUDRATE=

2. Configure telemetry protocol and OSD options in osdconfig.txt (only on the GroundPi)​

  • Choose the telemetry protocol used, Mavlink is default, other options supported are Frsky and Lightweight telemetry (LTM). E.g.: #define LTM
  • Choose graphical OSD options you would like to have enabled in osdconfig.txt. Should be self-explanatory.

Note: Inav users must enable the Compass by settings COMPASS_INAV=true

Generally, try to configure your flight control so that it does not send out unnecessary large amounts of data to keep the packet rate as low as possible.

The received telemetry data stream will also be saved in text and raw form to an USB memory stick automatically for later review.

3. Wiring​

  • Connect the serial port TX pin of your flight controller to the serial port RX pin on the Pi. WARNING: The Pi uses 3.3V logic level on the serial ports, make sure your flight control also uses 3.3V. 5V might destroy the Pi serial port! So don't connect the + 5V ! (See https://pinout.xyz/ for pinout).
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