#!/bin/python

import time
import datetime
import serial
from decimal import *
import thread
import os, sys
import struct

TTY_IR = '/dev/ttyUSB0'

# Voltcraft IR thermometer serial communication initialization
ser = serial.Serial()
ser.baudrate = 9600
ser.port = TTY_IR

try:
    ser.open()
except:
    print "Thermometer is not connected, can't open /dev/ttyUSB0"
    sys.exit()

# ### INITIALIZATION  ###

# read line to overcome possible corrupted data
def detect_frame():
    print "> Detecting frame"
    while True:
        data = ser.read(1)
        if data[0].encode('hex') == "aa":
            print "> Frame Detected"
            break

detect_frame()

# Voltcraft IR 2200-50D USB data stream decoding (should be compatible with other Voltcraft IR USB thermometers)
def temp_get_ir():
    data = ""

    # read data from the serial port - 17 bytes
    try:
        data = ser.read(17)

        #for character in data:
        #    print character.encode('hex'),

        if data[16].encode('hex') != "aa":
            print "> Frame Lost"
            detect_frame()
            return temp
    except:
        print "> IR Data stream failed?"

    return (float (struct.unpack("<L", data[4]+""+data[3]+"\x00\x00")[0]) / 10, float (struct.unpack("<L", data[6]+""+data[5]+"\x00\x00")[0]) / 10)


# get data from IR and TC
data = temp_get_ir()
temp_ir = data[0]
temp_tc = data[1]