ds18b20.py

import os
import time

os.system('modprobe w1-gpio')
os.system('modprobe w1_therm')

temp_sensor = '/sys/bus/w1/devices/28-0215635d39ff/w1_slave'

def temp_raw():
    f = open(temp_sensor, 'r')
    lines = f.readlines()
    f.close()
    return lines

def read_temp():
    lines = temp_raw()
    while lines[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        lines = temp_raw()
    temp_output = lines[1].find('t=')
    if temp_output != -1:
        temp_string = lines[1].strip()[temp_output+2:]
        temp_celsius = float(temp_string)/1000.0
        return temp_celsius

while True:
    print(read_temp())
    time.sleep(1)