PWM Generator for Raspberry Pi

README.md

Raspberry Pi PWM

This Python3 script was created to generate a square wave pattern from the GPIO of the Raspberry Pi. This signal was used to inject a signal into an electronics project, but could be used as the basis for any PWM needs.

The script is configured to output the signal on pin 12 (GPIO18). Other pins which may be used are pin 32 (GPIO12) and pin 33 (GPIO13). Standard pin numbers (GPIO.BOARD) are used, Broadcom numbering (GPIO.BCM) may be used if desired by editing the appropriate line.

Configuration:

• pwmPin: Board Pin (change GPIO.BOARD to GPIO.BCM to use Broadcom numbering)
• dutyCycle: Duty cycle in percent
• freq: Pulse frequency in Hz

generator.py

#!/usr/bin/python3

import RPi.GPIO as GPIO
import sys
from time import sleep


pwmPin = 12         # GPIO18 (PWM0)
dutyCycle = 10.0    # 10% duty cycle
freq = 190          # 190 Hz (190 times/second)


def spinning_cursor():
    while True:
        for cursor in '|/-\\':
            yield cursor


def main():
    spinner = spinning_cursor()

    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(pwmPin,GPIO.OUT)
    pwm = GPIO.PWM(pwmPin,freq)
    pwm.start(dutyCycle)

    print("\nOutputting a {}% duty cycle PWM at {}hz on pin {}.".format(dutyCycle, freq, pwmPin))
    print("Ctrl-C to quit.")

    try:
        while (True):
            sys.stdout.write(next(spinner))
            sys.stdout.flush()
            sys.stdout.write('\b')
            sleep(0.1)

    except KeyboardInterrupt:
        print('\n\nKeyboard interrupt.')

    finally:
        spinner = None
        pwm.stop()
        GPIO.cleanup()

    return


if __name__ == "__main__":
    main()
    exit(0)