I am experiencing an issue where my Pixhawk 6X is not recognizing the signal from the RadioMaster R81 receiver. The RadioMaster TX16S Mark2 controller binds successfully to the R81 receiver, but the Pixhawk does not detect the signal when connected to the RC IN port. The receiver’s LED is solid red, and probing the output shows a 1000 Baud signal, which I expect from the SBUS protocol. However, when attempting to calibrate the radio in QGroundControl, I receive the “Radio Not Ready: Please turn on transmitter” message. Additionally, when running listener input_rc
in the MAVLink console, I see “never published.”
Steps Taken:
- Updated Pixhawk firmware via QGroundControl.
- Set the
RC_INPUT_PROTO
parameter to SBUS. - Checked signal output; confirmed 1000 Baud SBUS signal.
- Checked the MAVLink console and found no data published on input_rc.
Setup:
- Drone: Holybro X650 with Pixhawk 6X, 433MHz SIK radios, 6S 5200mAh battery.
- Radio Controller: RadioMaster TX16S Mark2 (FrSky D8 Compatible).
- RC Receiver: RadioMaster R81, 8 channels, SBUS (Inverted).
- Firmware: PX4 v1.15.2, QGroundControl v4.4.3.
It appears the RC IN connection is not detected. Is this a common issue with PX4, or could it be a configuration problem? How can I troubleshoot and resolve this?