Run a GPIO pin based on temp

temp.py

'''
Run an efficient loop that checks on the RP2 temperature every second.

If the tempt exceeds a threshold, turn the fan on until the next check.

pip install gpiozero
'''

from gpiozero import LED
from time import sleep
from subprocess import PIPE, Popen
import logging, sys

SLEEP_DURATION = 10
TEMP_THRESHOLD = 50
fan = LED(17)
fan_state = False

logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)

def get_cpu_temperature():
    """get cpu temperature using vcgencmd"""
    process = Popen(['vcgencmd', 'measure_temp'], stdout=PIPE)
    output, _error = process.communicate()
    return float(output[output.index('=') + 1:output.rindex("'")])

def main():
    global SLEEP_DURATION, TEMP_THRESHOLD, fan, fan_state
    while True:
        logging.debug('Running loop')
        temp = get_cpu_temperature()
        logging.info('Temp: %f', temp)
        logging.info('Fan State: %r', fan_state)

        if temp > TEMP_THRESHOLD:
            if fan_state == False:
                fan.on()
                fan_state = True
        else:
            fan.off()
            fan_state = False
        sleep(10)

main()