rfid.py

#!/usr/bin/env python

import datetime, serial, subprocess, sys, time

DEVICE='/dev/cu.usbserial-A7006gOH'
IDS={
    '28001D71E1': 'Ross',
    '0800D9D1AB': 'Steve',
    '2200562718': 'Edd',
    '2500718C43': 'Danny',
}

def puts(msg):
    sys.stdout.write(msg + "\n")
    sys.stdout.flush()

def beep():
    subprocess.call(["/bin/echo",chr(7)])

def rfid_reader(device=DEVICE, ids=None):
    def setDTRHigh():
        ser.setDTR(0)
        beep()
    
    def setDTRLow():
        time.sleep(0.5)
        ser.setDTR(1)
    
    puts("Opening " + device)
    ser=serial.Serial(device, 2400, timeout=1)

    last_id=None
    last_id_time=None
    delta=datetime.timedelta(seconds=3)
    
    try:
    
        while ser.isOpen():
            data=ser.readline().strip()
    
            if not data:
                continue
            
            # Check for duplicates
            now=datetime.datetime.now()
            if last_id == data and (now - last_id_time < delta):
                continue
            
            # All good, record last id and timestamp
            last_id=data
            last_id_time=now
                
            if not ids:
                setDTRHigh()
                yield data
                setDTRLow()
    
            else:
                # Do mapping of ids onto values...
                id=ids.get(data, False)
    
                if id: 
                    setDTRHigh()
                    yield id
                    setDTRLow()
                
    except KeyboardInterrupt, e:
        ser.close()
        raise e

if __name__ == "__main__":
    try:
        for id in rfid_reader():
            puts(id)
    except KeyboardInterrupt, e:
        sys.exit(0)