I'm trying to get a pixracer to run with an FrSky D8R-XP receiver. No luck so far: qGroundControl in radio calibration reports "0 Channels detected. At least 5 are required".
using a logicanalyzer as well as an CC3D flight controller I could confirm that the transmitter + receiver works as intended. I'm pretty sure it's wired up to PX4 correctly as well. I now suspect CPPM parsing not to work. Form a quick look into the firmware (drivers/px4fmu/fmu.cpp), there seems some autodetection between cppm, sbus, and three others going on. But no way to set/force one of the protocols.
Is this a known problem - is there some setting that I did not see? I could not find anything relevant. Or is there a way to debug this specifically?
Thanks and best regards,