#!/usr/bin/python3

#

# Demonstrates use of an ADC input to control LED brightness

#

# uses PWM output to control D1 on Wombat board (GPIO 4)

# with duty cycle set by analog input CH0 (pot RP1)

#

# outputs complementary PWM output on D2 (GPIO 17)

# (D1 lit while D2 off and vice versa)

#

# v1.0 28/4/15

#

# David Meiklejohn

# Gooligum Electronics

#

import RPi.GPIO as GPIO

from wombat import readadc

# pin assignments

adc_chan = 0 # use analog input CH0

led1 = 4 # LED D1 on GPIO 4 (active high)

led2 = 17 # LED D2 on GPIO 17 (active high)

# configure I/O

GPIO.setwarnings(False)

GPIO.setmode(GPIO.BCM)

# configure pins

GPIO.setup(led1, GPIO.OUT)

GPIO.setup(led2, GPIO.OUT)

# setup PWM outputs

p1 = GPIO.PWM(led1, 100) # use 100 Hz for both

p2 = GPIO.PWM(led2, 100)

p1.start(0) # D1 initially off

p2.start(100) # D2 initially on (duty cycle = 100)

try:

while True:

# calculate duty cycle from current value (0-1023) of ADC input

dc = readadc(adc_chan)/1023*100

# adjust PWM outputs

p1.ChangeDutyCycle(dc)

p2.ChangeDutyCycle(100-dc)

except KeyboardInterrupt:

p1.stop()

p2.stop()

GPIO.cleanup()