DS18B20.py

# read temperature from DS18B20
# https://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing/hardware

# TODO command line args for time to run/num iterations
# TODO command line args for output file
# TODO run this on startup so I can run it with no network connection

import re
import datetime
import os
import time

rootDir = '/sys/bus/w1/devices/'
sensorDir = ""
for dirName, subdirList, fileList in os.walk(rootDir):
    for subdir in subdirList:
        if re.search("28-[\da-f]+", str(subdir)):
            sensorDir = subdir
sensorReadFile = rootDir + sensorDir + "/w1_slave"

outputFile = open('temp-' + str(datetime.datetime.now().replace(microsecond=0)),'a+')

while True:

    # read the sensor data
    sensorReadResult = open(sensorReadFile, "rb").read()

    # parse the output from the sensor file read
    m = re.search(".* : crc=.. (\w+)\n.* t=(\d+)", sensorReadResult)
    if not m or "YES" != m.groups()[0]:
        raise sensorReadResult

    degC = int(m.groups()[1]) / 1000.0
    degF = degC * 9.0 / 5.0 + 32
    #print "%.2f" % degF

    line = str(datetime.datetime.now().replace(microsecond=0)) + "\t%.2f" % degF
    print line
    outputFile.write(line + '\n')
    outputFile.flush()
    time.sleep(1)