Beaglebone Speaker DAC test GPIO driver

import os
import time



#Functions
def setDirection(pin, direction):
    pin = str(pin)
    direction = str(direction)

    os.system("echo "+pin+" > /sys/class/gpio/export")
    os.system("echo "+direction+" > /sys/class/gpio/gpio"+pin+"/direction")


def setPinValue(pin, pinValue):
    pin = str(pin)
    pinValue = str(pinValue)

    os.system("echo "+pinValue+" > /sys/class/gpio/gpio"+pin+"/value")


#Begin Script
#######################

#Turn on P8 Pin 40
#Data Line 0
setDirection(77, "out")

#Turn on P8 Pin 42
#Data Line 1
setDirection(75, "out")

#Turn on P8 Pin 44
#Data Line 2
setDirection(73, "out")

#Turn on P8 Pin 46
#Data Line 3
setDirection(71, "out")

#Turn on P8 Pin 45
#Data Line 4
setDirection(70, "out")

#Turn on P8 Pin 43
#Data Line 5
setDirection(72, "out")

#Turn on P8 Pin 41
#Data Line 6
setDirection(74, "out")

#Turn on P8 Pin 39
#Data Line 7
setDirection(76, "out")

startValue = 0

while True:
    startValue = startValue + 1
    if startValue > 255:
        startValue = 0

    #Reset datapins before setting datapins
    #setPinValue(77, 0)
    #setPinValue(75, 0)
    #setPinValue(73, 0)
    #setPinValue(71, 0)
    #setPinValue(70, 0)
    #setPinValue(72, 0)
    #setPinValue(74, 0)
    #setPinValue(76, 0)

    #Turn on datalines accordingly
    #convert dec to binary
    binary_value = bin(startValue)
    binary_value = binary_value[2:]

    print binary_value

    if binary_value.__len__() == 1:
        binary_value = "0000000"+str(binary_value)

    if binary_value.__len__() == 2:
        binary_value = "000000"+str(binary_value)

    if binary_value.__len__() == 3:
        binary_value = "00000"+str(binary_value)

    if binary_value.__len__() == 4:
        binary_value = "0000"+str(binary_value)

    if binary_value.__len__() == 5:
        binary_value = "000"+str(binary_value)

    if binary_value.__len__() == 6:
        binary_value = "00"+str(binary_value)

    if binary_value.__len__() == 7:
        binary_value = "0"+str(binary_value)





    #Data Line 0
    ########
    if binary_value[7] == "1":
        setPinValue(77, 1)
    else:
        setPinValue(77, 0)
    ########


    #Data Line 1
    ########
    if binary_value[6] == "1":
        setPinValue(75, 1)
    else:
        setPinValue(75, 0)
    ########


    #Data Line 2
    ########
    if binary_value[5] == "1":
        setPinValue(73, 1)
    else:
        setPinValue(73, 0)
    ########


    #Data Line 3
    ########
    if binary_value[4] == "1":
        setPinValue(71, 1)
    else:
        setPinValue(71, 0)
    ########


    #Data Line 4
    ########
    if binary_value[3] == "1":
        setPinValue(70, 1)
    else:
        setPinValue(70, 0)
    ########


    #Data Line 5
    ########
    if binary_value[2] == "1":
        setPinValue(72, 1)
    else:
        setPinValue(72, 0)
    ########


    #Data Line 6
    ########
    if binary_value[1] == "1":
        setPinValue(74, 1)
    else:
        setPinValue(74, 0)
    ########


    #Data Line 7
    ########
    if binary_value[0] == "1":
        setPinValue(76, 1)
    else:
        setPinValue(76, 0)
    ########


    #time.sleep(1)