树莓派-PCF8591（AD DA）实验

#!/usr/bin/env python

import PCF8591 as ADC

def setup():

	ADC.setup(0x48)

def loop():

	while True:

		print ADC.read(0)

		ADC.write(ADC.read(3))

def destroy():

	ADC.write(0)

if __name__ == "__main__":

	try:

		setup()

		loop()

	except KeyboardInterrupt:

		destroy()

#!/usr/bin/env python

#------------------------------------------------------

#

#		This is a program for PCF8591 Module.

#

#		Warnng! The Analog input MUST NOT be over 3.3V!

#    

#		In this script, we use a poteniometer for analog

#   input, and a LED on AO for analog output.

#

#		you can import this script to another by:

#	import PCF8591 as ADC

#	

#	ADC.Setup(Address)  # Check it by sudo i2cdetect -y -1

#	ADC.read(channal)	# Channal range from 0 to 3

#	ADC.write(Value)	# Value range from 0 to 255		

#

#------------------------------------------------------

import smbus

import time

# for RPI version 1, use "bus = smbus.SMBus(0)"

bus = smbus.SMBus(1)

#check your PCF8591 address by type in 'sudo i2cdetect -y -1' in terminal.

def setup(Addr):

	global address

	address = Addr

def read(chn): #channel

	if chn == 0:

		bus.write_byte(address,0x40)

	if chn == 1:

		bus.write_byte(address,0x41)

	if chn == 2:

		bus.write_byte(address,0x42)

	if chn == 3:

		bus.write_byte(address,0x43)

	bus.read_byte(address) # dummy read to start conversion

	return bus.read_byte(address)

def write(val):

	temp = val # move string value to temp

	temp = int(temp) # change string to integer

	# print temp to see on terminal else comment out

	bus.write_byte_data(address, 0x40, temp)

if __name__ == "__main__":

	setup(0x48)

	while True:

		print 'AIN0 = ', read(0)

		print 'AIN1 = ', read(1)

		tmp = read(0)

		tmp = tmp*(255-125)/255+125 # LED won't light up below 125, so convert '0-255' to '125-255'

		write(tmp)

#		time.sleep(0.3)