I’ve got an XIAO that I’m using to send PWM signals to a motor controller, nothing special. The problem is that the motors whine quite loudly, because the PWM frequency is in the human hearing range. I am currently using the Arduino IDE to write my code, and I am simply using the analogWrite() function to set the PWM duty cycle. Is there a way to increase the PWM frequency by e.g. changing the prescale value for the appropriate timers?
I apologize if this has already been covered, but I can’t seem to find anything that clearly solves this problem (which is surprising, considering how common I imagine this problem is).
I may have finally found something… It is not specific to the XIAO, but is for anything running a SAMD21:
https://shawnhymel.com/1710/arduino-zero-samd21-raw-pwm-using-cmsis/
I’ll give it a try and see what I can come up with.
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Well it took me long enough, but I finally cracked it. I was able to set the XIAO’s PWM frequency to 20kHz, which is out of (most) human hearing range. Sorry I wasn’t nice enough to make this its own stand-alone repo, but here is the relevant code within my robot’s repository. See the wiring_analog_extras.cpp/.h, specifically.
https://github.com/SaltyHash/BWO/tree/master/src/arduino/motor_control
Hope this helps some of you out!
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Many thanks for this tip and library code. Really saved me big time with a project I am working on.
Cheers!
