Using PWM Output from Raspberry

[juergschwarz]

Im am using openplc with unipi 1.1 and raspberry 3. The unipi output A0 is only analog 0-10V and not a real digital PWM signal.

To control a servo i need a real digital PWM signal. How is it possible to use this in parallel to unipi?

[juergschwarz]

Ok now i send a pic and a video

And here the video

https://link.eu1.storjshare.io/jwsnlnnvc4qlkvuxqltk7kygvoaq/freigabenallgemein%2FVID_20220117_161837.mp4

As can be seen, the frequency changes rather than the length of the period

[Martin Kudláček]

Hello @juergschwarz,
none of the outputs are capable of being drived by PWM signal. The analog output has a filter + amplifier to create smooth(ish) output. This cannot be bypassed.

Other outputs are the relay outputs - and if your frequency is not in tens of seconds (or better in minutes), then I would not advise to use PWM to drive them.

You can try using some I2C expander connected to the external I2C bus.

Best regards,
Martin

[juergschwarz]

@Martin-Kudláček said in Using PWM Output from Raspberry:

Hello @juergschwarz,
none of the outputs are capable of being drived by PWM signal. The analog output has a filter + amplifier to create smooth(ish) output. This cannot be bypassed.

Other outputs are the relay outputs - and if your frequency is not in tens of seconds (or better in minutes), then I would not advise to use PWM to drive them.

You can try using some I2C expander connected to the external I2C bus.

Best regards,
Martin

Ok i forgot this info: I try to use the raspberry output %QW0 separately to generate this PWM signal and not the A0 from unipi. I my video you can see the output of %QW0.

[juergschwarz]

@juergschwarz Ok it works. had to change the position in raspberry.cpp to the end of
void initializehardware()

and the Initial values higher (4000 and 6000)

Thanks