Pixhawk 2 + TBS CrossFire = Radio Failsafe not detected by FC

On Tue, 22 May at 3:27 AM , Miguel qkidamon@gmail.com wrote:
I’m using TBS Crossfire in a arducopter drone with pixhawk 2.1 flight controller.
I have setup Crossfire RX to send rc commands trought MAVLINK telemetry port on the flight controller.

The RX failsafe is set to cut signal to servos but when i switch off tranmiter the flight controller does not detect the link has been lost and rc inputs keep their last received values and this is the cause for me to be unable to properly configure the arducopter RC failsafe.

I have made the next question to TBS support team:

“When RK failsafe is configured to cut off servo signal output, all outputs are cut? Even outputs #7 and #8 where mavlink tx an rx are used to pass rc commands to FC.”

And here is their answer:

"Hi Miguel,
i spoke with our lead engineers and they told me “Crossfire stops sending RC frames over MAVLink in case of a failsafe if failsafe type is cut. So there is a issue on the Arducopter side.” "

Should i use low pwm values failsafe to be able to detect radio link is lost ? Is there any way to configure arducopter to detect rc link is not present when rc commands are issued throught mavlink from TBS Crossfire RX?


I have successfully configured the crossfire with my pix2 (it took a while):

  1. Taranis external RF Config: CRSF CH 1-16
  2. Connected CH1 to RC-In and configured the channel to be ppm in the Crossfire Menu (TX)
  3. Connected CH7/CH8 to Telem2 Port (RX/TX) and configured this in the Crossfire Menu
  4. Disable RC by Mavlink in the Crossfire Menu
  5. Configure in Mission Planner Serial2 according to the Crossfire Manual page 30
  6. This is the important step: restart everything - pix2, tx…

I have 12 Channels now and mavlink over bluetooth is working (kind of slow). The only issue that I don’t like is that if I have a short telemetry-lost I have to manually reconnect mission planner to get telemetry data to MP again.

Hope this helps.

It seems a good chance. I’ll give it a try and confirm.
Thanks a lot.