PWM example on Intel Galileo/Edison

pwm.py

#!/usr/bin/python

import mraa
import time

PWM_PIN = 5
pwm = mraa.Pwm(PWM_PIN)


"""
Control the period with "period_us"

            +----------------+                +----------------+                |
            |                |                |                |                |
            |                |                |                |                |
            |                |                |                |                |
            |                |                |                |                |
            |                |                |                |                |
            |                |                |                |                |
            |                |                |                |                |
            |                |                |                |                |
            +                +----------------+                +----------------+
            ^                                 ^
            |                                 |
            |<---------- Period ------------->|
            |               ^                 |
            |               |                 |
                            | 
            pwm.period_us(5000)
  
"""  

pwm.period_us(5000)        # Set the period as 5000 us or 5ms

pwm.enable(True)           # enable PWM
value = 0

delta = 0.05               # Used to manipulate duty cycle of the pulse

while 1:
    
    if (value >= 1):
        # Itensity at max, need to reduce the duty cycle, set -ve delta
        value = 1
        delta = -0.05
    elif (value <=0):
        value = 0
        # Intensity at lowest, set a +ve delta
        delta = 0.05
        
    """
    Control the duty cycle with "write"
            +------+                            +------+                            
            |      |                            |      |                           
            |      |                            |      |                           
            |      |                            |      |                           
            |      |                            |      |                           
            |      |                            |      |                           
            |      |                            |      |                           
            |      |                            |      |                           
            |      |                            |      |                           
            +      +----------------------------+      +---------------------------+
            ^      ^
            |      |
            |<---->|
                ^
                |
                |
     pwm.write(0.2)
    """
    
    pwm.write(value) # Set the duty cycle
    
    value = value + delta

    time.sleep(0.5)