All /sys/kernel/rcio/rcin channels return 0, no matter where the sticks are. I know the receiver is working because I can run servos off it and they are controlled normally. Only PPM doesn’t seem to come through. I’m wondering if there’s a configuration or setting I might have missed, or something special for 6 channels vs. 8, or for my receiver vs. FrSky brand (are the number of channels and frequency detected automatically?)
My best guess for now is that there’s some timing incompatibility between the PPM decoder library used by Navio and the Spektrum/OrangeRX output PPM. Without buying a whole new transmitter, I’m hoping to find another DSMX receiver that is tested to work with Navio2. In the meantime, without an oscilloscope, I’ll try debugging with an Arduino decoder.
My problem may be related to: Spektrum DX6i -> Lemon RX DSMX -> PPM - Problems
UPDATE
The problem is not solved but I can confirm that my receiver is outputting a PPM signal, which I can decode using an arduino and the code from here.
I am reading 6 channels, with pulses ranging from ~1052us (min) to ~1900us (max) with ~1480us as midway (0-point.)
Now the question remains: why can’t the Navio2 decode this? It seems like if this is an issue with timing or # channels, I may need to alter APM and recompile from scratch…