RFID @catdoor for Twitter, Phase 1

Simple concept, put an RFID chip on your cat and a reader by the door. Tweet whenever the cat uses the door.The reader is a APSX 15.56MHZ RW-210 reader. The RFID is a Sakymat LOGI TAG aka “laundry tag”. The server is a Hush mini-ITX machine with a 32G CF chip instead of a hard drive. The code is written in Python running on Fedora Core 10.Pictures will follow, the code is below:

This is the first draft of the catdoor.py

[geshi lang=”python” nums=”0″ ]

#!/usr/bin/python

import twitter
from apsx import *rfid_open(0)
 api = twitter.Api(username='catdoor', password='xxxxxx')# let's  blink some
 #
 for i in range(1,50) :
 red_LED(True)
 green_LED(True)
 red_LED(False)
green_LED(False)while 1 :

# get a button
 #
 b = read_UID()
 sleep(.1)

if b :
 green_LED(True)
 print 'got a button: %s' % hexer(b)
 status = api.PostUpdate('Cat at the door UID: %s' % hexer(b))
 print 'TWEET! | %s' % status.text

while b :
 sleep(1)
 b = read_UID()

green_LED(False)

else :
 red_LED(True)
 sleep(.1)
 red_LED(False)
 sleep(.9)

[/geshi]

The apsx.py code to talk to the APSX board is here:

 

[geshi lang=”python” nums=”0″ ]

 #

#  Python code to talk to a APSX RFID Module
 #

 #  Not a complete set of functions but enough to get my cat door working.

 #

 #  10 Jan 09   JV       - Created

 #
 import serialser = NonePresetValue = 0xffff
 Polynomial = 0x8408

def crc(DataBytes) :
 "APSX ISO 15693 CRC-16"

CRCValue = PresetValue
 for b in DataBytes :
 CRCValue = CRCValue ^ ord(b)

for j in range(0,8) :
 if CRCValue & 1 :
 CRCValue = (CRCValue>>1) ^ Polynomial
 else :
 CRCValue >>= 1

CRCValue = ~CRCValue - 65536
 CRCValue &= 0xffff
 CRCLSB = CRCValue % 256
 CRCMSB = CRCValue >> 8

return (CRCLSB, CRCMSB)

def read_UID() :
 "Read a UID or None if not exactly 12 bytes"
 ser.write('\0xfa')
 s = ser.read(12)
 if len(s) == 12 :
 return s
 return None

def red_LED(on) :
 if on :
 ser.write('\xfd')
 else :
 ser.write('\xfc')
 sleep(.02)

def green_LED(on) :
 if on :
 ser.write('\xff')
 else :
 ser.write('\xfe')
 sleep(.02)

def rfid_open(port) :
 "call to open the serial port"

global ser
 if ser :
 if ser.isOpen() :
 ser.close()
 ser = serial.Serial(port, 19200, timeout=1)
 print ser.portstr

def hexer(s) :
 "return a hex string"

h = ''
 for c in s :
 h += '0x%02x ' % ord(c)
 return h

#red_LED(True)
 #green_LED(True)
 #red_LED(False)
 #green_LED(False)

#ser.close()

[/geshi]