InputTransducers.py

import RPi.GPIO as GPIO
from time import sleep

class InputTransducer:
    def __init__( self, *, name="InputTransducer", pin=0 ):
        self.name = name
        self.pin = pin
        
    def getValue():
        return 0
        
class AnalougeInput( InputTransducer ):

    def getValue():
        lastMeasure = 0
        # Discharge capacitor
        GPIO.setup( self.pin, GPIO.OUT )
        GPIO.output( self.pin, GPIO.LOW )
        sleep( 0.1 )

        GPIO.setup( self.pin, GPIO.IN )
        # Count loops until voltage across
        # capacitor reads high on GPIO
        # Unreliable, but perhaps better than enforcing delays
        while ( GPIO.input( self.pin ) == GPIO.LOW ):
            lastMeasure += 1

        return lastMeasure
        
class DigitalInput( InputTransducer ):
    
    def __init__( self, *, id=None ):
        self.deviceID == id
    
    def getValue():
        try:
            mytemp = 0
            filename = 'w1_slave'
            f = open( '/sys/bus/w1/devices/' + self.deviceID + '/' + filename, 'r' )
            line = f.readline() # read 1st line
            crc = line.rsplit( ' ',1 )
            crc = crc[ 1 ].replace( '\n', '' )
            
            if crc=='YES':
            
              line = f.readline() # read 2nd line
              mytemp = line.rsplit( 't=',1 ) / float( 1000 )
              
            else:
            
              mytemp = -1
              
            f.close()

            return int( mytemp[ 1 ] )

          except:
          
            return -1