On Navio2 PWM, ADC, SBUS and PPM are integrated in Linux sysfs allowing for easy access from any programming language. Sysfs is a virtual file system that exports info about kernel subsystem and hardware devices.
For instance, sysfs provides easy access to attributes of Navio2's PWM (/sys/class/pwm/pwmchip0/) or RC input structures (/sys/kernel/rcio/rcin/).
If you face issue with PWM generating or RC input decoding, check the status of Navio2's onboard RCIO. To get the status, execute this command:
pi@navio:~ $ cat /sys/kernel/rcio/status/alive
RCIO is powered on and detected by Raspberry Pi if the result of above operation is
0 shows that RCIO is not connected.
If the above command outputs
0, check check the hardware connection between Navio2 and Raspberry Pi. Navio2 should be fixed using screws as stated in Hardware setup guide.