Hi, I’m trying to control a servo motor with uLisp on an RPi Pico. The motor expects the PWM frequency to be 50Hz. Directly using analogwrite makes it rotate erratically, and I wonder if it is because the frequency is wrong.
In MicroPython you can set the PWM frequency on a pin:
from machine import Pin, PWM
servo = PWM(Pin(16))
servo.freq(50) # 50Hz, pulses every 20ms
How do I adjust the PWM frequency like this in uLisp? Thanks!
uLisp doesn’t currently implement a function to allow you to change the PWM frequency, but you could add your own calls to the Arduino core as described here:
I’ve had a look at the reference for the RP2040 Arduino core, and it seems that there is the function you need:
void analogWriteFreq(uint32_t freq)
However, the lowest frequency it supports is 100Hz.
A better bet might be to implement uLisp functions to give access to the Servo library:
I’d be happy to give some help if you get stuck.