Entry 1: Interfacing ADC using Parallel port with Python

This Python code will suffice the need of interfacing an ADC (analog-to-digital converter) using a Parallel Port. Tested with ADC0804 (8-bit ADC ).

'''This module facilitates ADC interfacing in Python using a Parallel port'''

__author__ = 'Aivin V. Solatorio'

import parallel

import ctypes

_ppt = ctypes.windll.simpleio

_ppt.init()

class ParallelADC(object):

'''Definition of ADC interfacing class'''

def __init__(self):

self.dataAdr = 0x0378

self.statAdr = self.dataAdr + 1

self.ctrlAdr = self.dataAdr + 2

def getData(self):

'''Acquires signal from data register'''

return _ppt.inp(self.dataAdr)

def setCtrl(self, val):

'''Dictates the value of control register'''

_ppt.outp(self.ctrlAdr, val)

def getStat(self):

'''Acquires value of status register'''

return _ppt.inp(statAdr)

'''Start of data gathering'''

gather_time = 100 #100 number of sample points

ADC = ParallelADC()

for i in xrange(gather_time):

lc = 0

ADC.setCtrl(0x32) #initializes ADC to start

ADC.setCtrl(0x36) #converting signal

while ((ADC.getStat() & 8) == 0) and (lc != 256):

lc += 1 #wait for ADC to finish converting

if (lc == 256):

print "Timed Out, check device or connection!"

else:

ADC.setCtrl(0x37)

value = ADC.getData() & 0xFF

ADC.setCtrl(0x36)

print "The ADC reading is: ", value #prints out ADC value