Recent changes to PWM

Discussion for PWM page

Loxaan Oxyde — Thu, 31 May 2018 17:35:59 -0000

pip install RPi.GPIO

PWM modified by Ben Croston

Ben Croston — Sat, 21 Dec 2013 22:51:23 -0000

--- v1
+++ v2
@@ -1,29 +1,35 @@
 # Using PWM in RPi.GPIO

-To create a PWM instance: 
-    
+To create a PWM instance:
+
+    :::python
     p = GPIO.PWM(channel, frequency)

-To start PWM: 
-    
+To start PWM:
+
+    :::python
     p.start(dc)   # where dc is the duty cycle (0.0 <= dc <= 100.0)

-To change the frequency: 
-    
+To change the frequency:
+
+    :::python
     p.ChangeFrequency(freq)   # where freq is the new frequency in Hz

-To change the duty cycle: 
-    
+To change the duty cycle:
+
+    :::python
     p.ChangeDutyCycle(dc)  # where 0.0 <= dc <= 100.0 

-To stop PWM: 
-    
+To stop PWM:
+
+    :::python
     p.stop()

 Note that PWM will also stop if the instance variable 'p' goes out of scope. 

-An example to blink an LED once every two seconds: 
-    
+An example to blink an LED once every two seconds:
+
+    :::python
     import RPi.GPIO as GPIO
     GPIO.setmode(GPIO.BOARD)
     GPIO.setup(12, GPIO.OUT)
@@ -34,8 +40,9 @@
     p.stop()
     GPIO.cleanup()

-An example to brighten/dim an LED: 
-    
+An example to brighten/dim an LED:
+
+    :::python
     import time
     import RPi.GPIO as GPIO
     GPIO.setmode(GPIO.BOARD)

PWM modified by Anonymous

Anonymous — Wed, 18 Dec 2013 16:59:32 -0000

Using PWM in RPi.GPIO

To create a PWM instance:

p = GPIO.PWM(channel, frequency)

To start PWM:

p.start(dc)   # where dc is the duty cycle (0.0 <= dc <= 100.0)

To change the frequency:

p.ChangeFrequency(freq)   # where freq is the new frequency in Hz

To change the duty cycle:

p.ChangeDutyCycle(dc)  # where 0.0 <= dc <= 100.0

To stop PWM:

p.stop()

Note that PWM will also stop if the instance variable 'p' goes out of scope.

An example to blink an LED once every two seconds:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)

p = GPIO.PWM(12, 0.5)
p.start(1)
input('Press return to stop:')   # use raw_input for Python 2
p.stop()
GPIO.cleanup()

An example to brighten/dim an LED:

import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)

p = GPIO.PWM(12, 50)  # channel=12 frequency=50Hz
p.start(0)
try:
    while 1:
        for dc in range(0, 101, 5):
            p.ChangeDutyCycle(dc)
            time.sleep(0.1)
        for dc in range(100, -1, -5):
            p.ChangeDutyCycle(dc)
            time.sleep(0.1)
except KeyboardInterrupt:
    pass
p.stop()
GPIO.cleanup()