Can't get PWM to work


Cannot get the PWM to work (both in C++ and Python). Is there way to debug the PWM drivers.

Python error:

Traceback (most recent call last):
  File "", line 13, in <module>
    with navio.pwm.PWM(PWM_OUTPUT) as pwm:
  File "/home/pi/third_party/Navio2/Python/navio/", line 15, in __enter__
  File "/home/pi/third_party/Navio2/Python/navio/", line 34, in initialize
IOError: [Errno 5] Input/output error

C++ Error:
Can't init channel 0

Thanks in advance.

Hi @pkot,

Are you running the scripts that we provide as examples? Did you supply power to the servo rail?

Hi @liudmila.slepova , yes using the provided example scripts. and powered the servo railing.

Hi @pkot,

I see! Do other examples also fail to run?

Hi @liudmila.slepova, Looks like only RCInput and RCOutput examples are not working (tried both with and without powering the servo-rail); other examples are working fine.

Hi @pkot,

Just to make sure: are you running those examples with sudo? Do you work with the latest image?

I’ll try to run those myself to test it.

Hi @liudmila.slepova,

Yes, running in sudo and on the last image (emlid-raspbian-20200922.img.xz) from here.

After some debugging (tested it on a different RPi and it works), it’s the Raspberry Pi that’s the problem and not the Navio2 hat. I reflashed the image and tested it to no avail.

Do you know what could be an issue on the RPi that makes the servo rail not work?


Edit: Using Raspberry pi 4

Hi @pkot,

Sorry for the delayed response! I’m glad you’ve found the source of the issue.

I’m not sure but maybe because of the loose connection between Navio2 and the RPi board.

Yeah, it’s a bummer; pretty good RPI and a working navio2 board just can’t seem to get them working together. All other sensors work except the servo rail.

That’s quite strange, indeed. Unfortunately, I can hardly give any other clues on why this happens as it looks like an issue from the RPi side. If you power the servo rail the same way as on the other RPi, it should work the same way.

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