rpi hardware pwm

Access the hardware PWM of a Raspberry Pi with Python. More lightweight than alternatives.

Installation

1. On the Raspberry Pi, add dtoverlay=pwm-2chan to /boot/firmware/config.txt. This defaults to GPIO_18 as the pin for PWM0 and GPIO_19 as the pin for PWM1.
   • Alternatively, you can change GPIO_18 to GPIO_12 and GPIO_19 to GPIO_13 using dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4.
   • On the Pi 5, use channels 0 and 1 to control GPIO_12 and GPIO13, respectively; use channels 2 and 3 to control GPIO_18 and GPIO_19, respectively
   • On all other models, use channels 0 and 1 to control GPIO-18 and GPIO_19, respectively
2. Reboot your Raspberry Pi.
   • You can check everything is working on running lsmod | grep pwm and looking for pwm_bcm2835
3. Install this library: sudo pip3 install rpi-hardware-pwm

Examples

For Rpi 1,2,3,4, use chip=0; For Rpi 5, use chip=2

from rpi_hardware_pwm import HardwarePWM

pwm = HardwarePWM(pwm_channel=0, hz=60, chip=0)
pwm.start(100) # full duty cycle

pwm.change_duty_cycle(50)
pwm.change_frequency(25_000)

pwm.stop()

History

The original code is from jdimpson/syspwm, We’ve updated it to Python3 and made it look like the RPi.GPIO library’s API (but more Pythonic than that.), and we use it in Pioreactor bioreactor system.