Navio2 RCInput PPM frame requirements

What are the PPM frame requirements for Navio2? I’m using a 22.5ms, 8 channel frame and it’s not recognized by the PPM decoder.

Here’s my frame, the 8 channels are 12.5ms long with a 10ms sync.

Here’s the version:
Linux navio 4.4.6-4d0ae01-emlid-v7+ #3 SMP PREEMPT Wed Apr 6 13:25:26 MSK 2016 armv7l GNU/Linux

pi@navio:~ $ cat /sys/kernel/rcio/status/alive

It says it’s alive?
pi@navio:/sys/kernel/rcio/rcin $ sudo cat connected
Shouldn’t that be a ‘1’? How does it decide to mark it connected?

pi@navio:/sys/kernel/rcio/rcin $ lsmod
Module                  Size  Used by
cpufreq_stats           3463  0
brcmfmac              185969  0
brcmutil                5725  1 brcmfmac
cfg80211              438534  1 brcmfmac
rfkill                 15930  2 cfg80211
rcio_spi                2576  0
rcio_core               2231  1 rcio_spi
rcio_rcin               2184  1 rcio_core
rcio_adc                1556  1 rcio_core
rcio_pwm                2711  15 rcio_core
rcio_status             1545  1 rcio_core
bcm2835_gpiomem         3036  0
spi_bcm2835aux          4779  0
bcm2835_wdt             3225  0
spi_bcm2835             7222  0
i2c_bcm2708             4770  0
uio_pdrv_genirq         3100  0
uio                     8256  1 uio_pdrv_genirq
i2c_dev                 5859  2

I believe all the correct modules are loading, but below shows no RC input at all.

pi@navio:/sys/kernel/rcio/rcin $ ls
ch0  ch10  ch12  ch14  ch2  ch4  ch6  ch8  connected
ch1  ch11  ch13  ch15  ch3  ch5  ch7  ch9
pi@navio:/sys/kernel/rcio/rcin $ sudo cat ch0
pi@navio:/sys/kernel/rcio/rcin $ sudo cat ch1
pi@navio:/sys/kernel/rcio/rcin $ sudo cat ch2

Is there additional configuration for the PPM input that I’m missing?

This is a little over my head, but here is how the python bindings for Navio2 read the RCInputs.

There is a little more than I expected on reading a channel, and not for sure if seeking is doing something special. Just to rule out your seutp, could run the same rcinput sript and verify everything is working and may just be how you are reading stuff in. Just a wild guess!

That’s a good thought, but the ch0-ch14 listed in my /sys/kernel/rcio/ all have the value 0 (zero). I don’t think my STM32 thinks there is a valid input stream.

Out of curiousity, I unplugged this receiver from the Navio2 and plugged it into an APM 2.6 board. All 8 channels show up fine and can be calibrated from MissionPlanner.

I got my X4RSB today and connected up using S.BUS. It works fine. Is there a switch for PPM instead of SBUS?

No, it should be detected automatically.

What kind of receiver is that?

It is a Flysky 6ch PPM clone. Is the 3.3v PPM input signal what the Navio2 does not like? I have used this receiver successfully on the Phoenix flight sim, a Naze, a CC3D and a mini APM 2.6. The Navio2 was the first time I’ve had and issue with processing its signal.

Me,too. I have been used to the same model. but, no response! so I have been to give up…