PPM input on APM 2.6

I am using Arduplane 3.2.3 and an APM 2.6 with an FRSky X8R receiver with Sbus output. I Plug the Sbus into input 1 with inputs 2&3 linked to get the serial ppm recognised. On mission planner RC Calibration all the RC inputs are at .9mS (900) and nothing works. I definitely have serial output on the Sbus and the RC inputs operate correctly and can be calibrated when using the normal pwm inputs.

Any suggestions as to what is going on? Is this a feature that has been lost on the latest APM2.6 version hardware?


From what I understand, SBUS is different to PPM and it’s PPM that is supported by the APM. Pixhawk seems to cope well with both.

There is some info on YouTube about reflashing the APM encoder hardware to work with SBUS but it’s not something I’d consider doing. - youtube.com/watch?v=7Nqr4-cbyvI

Could always get a FrSky SBUS to CPPM converter - hobbyking.co.uk/hobbyking/st … coder.html

I would recommend you use an Frsky D4R-II receiver. It will output 8 channels of PPM directly when you jumper channels 3 and 4 together.

I never see the S.Bus to PPM converter in stock anywhere for some reason.

Hi. SBUS isn’t directly supported on APM. You will need a converter. This thread has some info:
This page shows you how to connect the cppm converter:
copter.ardupilot.com/wiki/common … nd-motors/

Thanks, Grant.

Thanks to all those who responded - I did not realise the Sbus was a Futaba protocol and not the same as PPM.

Thanks, Peter