temperature_parser.py

# Code from CamJam Edukit 2 - Sensors: Worksheet 3 - Temperature
# Uses a ‘Dallas DS18B20’ sensor
# Import Libraries
import os
import glob
import time

# Initialize the GPIO Pins
os.system('modprobe w1-gpio')  # Turns on the GPIO module
os.system('modprobe w1-therm')  # Turns on the Temperature module

# Finds the correct device file that holds the temperature data
base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'


# A function that reads the sensors data
def read_temp_raw():
    """
    Reads the whole output of the temperature sensor
    """
    with open(device_file, 'r') as f:
        lines = f.readlines()
    return lines


def get_temp():
    """
    Returns the current temperature in float
    """
    lines = read_temp_raw()  # Read the temperature 'device file'

    # While the first line does not contain 'YES', wait for 0.2s
    # and then read the device file again.
    while lines[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        lines = read_temp_raw()

    # Look for the position of the '=' in the second line of the
    # device file.
    equals_pos = lines[1].find('t=')

    # If the '=' is found, convert the rest of the line after the
    # '=' into degrees Celsius, then degrees Fahrenheit
    if equals_pos != -1:
        temp_string = lines[1][equals_pos+2:]
        temp_c = float(temp_string) / 1000.0

    return temp_c