pi_pwm_scope

I started testing my new Siglent SDS1104X-E oscilloscope.  I did square wave test for the probes at 10X.  I setup Arduino PWM to test.   This is the Raspberry Pi PWM.  I found the GPIO.PWM frequency is off.     I played with the setting and found 1149 is closes to 1 kHz.

pwm = GPIO.PWM(ledpin, 1000) had a scope reading of 888 Hz.

import RPi.GPIO as GPIO
import time
 
ledPin = 13
 
def setup():
    global pwm
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(ledPin, GPIO.OUT)
    GPIO.output(ledPin, GPIO.LOW)
    pwm = GPIO.PWM(ledPin, 1149) # Set Frequency to 1 KHz
    pwm.start(0) # Set the starting Duty Cycle
     
def loop():
    while True:
        pwm.ChangeDutyCycle(0)
            
         
def destroy():
    pwm.stop()
    GPIO.output(ledPin, GPIO.LOW)
    GPIO.cleanup()
     
if  __name__ == '__main__':
    setup()
    try:
        loop()
    except KeyboardInterrupt:
        destroy()

pwm.ChangeDutyCycle(0)

pwm.ChangeDutyCycle(25)

pwm.ChangeDutyCycle(50)

pwm.ChangeDutyCycle(75)

pwm.ChangeDutyCycle(100)