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Problems with PPM Input on OMNIBUSF4

Hello guys,
so my plan was to build a tricopter using this FC:


(Seems to be an OMNIBUSF4V1/V2 clone)

But when after connecting my iA6B receiver (with ppm enabled) to the sbus/ppm pin (with sbus jumper removed), I dont get any ppm signal on the Setup Page (sometimes no green bars at all and sometimes static green bars) . When i replace Arduplane 4.0.6 with INAV 2.5.0 however, it works like a charm with the exact same hardware configuration.

Since i suspected a wrong pin definition I had a look at the hardware definition files for the OMNIBUSF4 in INAV (https://github.com/iNavFlight/inav/blob/master/src/main/target/OMNIBUSF4/target.c) and Ardupilot (https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_HAL_ChibiOS/hwdef/omnibusf4pro/hwdef.dat with OMNIBUSF4 inheriting the RCIN directly from OMNIBUSF4PRO).

I’ve noticed that in INAV, the PPM RCIN is defined as
“DEF_TIM(TIM12, CH1, PB14, TIM_USE_PPM, 0, 0), // PPM” -> PB14
and in Ardupilot
“PB8 TIM4_CH3 TIM4 RCININT PULLDOWN LOW” ->PB8

So i cloned the ardupilot repo, changed this line to the INAV pin and timer channel but ppm input still wont work. What should i do?

Where can i get debug info regarding the RC PPM input?

Servers by jDrones