Increasing PWM frequency beyond 100 Hz

General
1

Hi I'm using a Raspberry Pi to drive a PWM output. I use this output to regulate a 0-20 mA circuit . converting the PWM voltage into current. However the library node-red-node-pi-gpiod only allows a maximum of 100 Hz. This is fine to drive an LED but in my case it results in a very noisy DC signal.
Due to the very low frequency it is difficult to use LF filtering ( the signal is actually not even 100 Hz its 68) I looked into using a DAC but I'm not sure if there is a library for one around where the hardware is reasonable is price.
After some research I fond that pin 18 & 19 on Pi 3 support hardware PWM. Dose someone knows how to use the library to set the frequency higher or knows of some method to get a variable stable DC voltage 0-3.3 out of a PWM od I2C DAC.

In advance thank you for your help.

2

Have you tried using the standard GPIO Out node instead of gpiod? It can go faster, but is less accurate so you might not benefit.

On the gpiod node I believe the underlying library can go much faster but the node does not support it, I am not sure why.

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