exec/temperature/DS18B20..temp_poll.py

   1 #!/usr/bin/env python3
   2 # Desc: Prints time and temperature reading
   3 # Output: [date (ISO-8601)],[date (Unix Epoch)],[temp (°C)]
   4 # Depends: python 3.3
   5 # Ref/Attrib: Raspberry Pi Temprature Sensor using the DS18B20; https://pimylifeup.com/raspberry-pi-temperature-sensor/
   6
   7 import os
   8 import glob
   9 import time
  10 from time import strftime
  11 import socket
  12
  13 os.system('modprobe w1-gpio')
  14 os.system('modprobe w1-therm')
  15
  16 base_dir = '/sys/bus/w1/devices/'
  17 device_folder = glob.glob(base_dir + '28*')[0]
  18 device_file = device_folder + '/w1_slave'
  19
  20 def read_temp_raw():
  21     f = open(device_file, 'r')
  22     lines = f.readlines()
  23     f.close()
  24     return lines
  25
  26 def read_temp():
  27     lines = read_temp_raw()
  28     while lines[0].strip()[-3:] != 'YES':
  29         time.sleep(0.2)
  30         lines = read_temp_raw()
  31     equals_pos = lines[1].find('t=')
  32     if equals_pos != -1:
  33         temp_string = lines[1][equals_pos+2:]
  34         temp_c = float(temp_string) / 1000.0
  35         temp_f = temp_c * 9.0 / 5.0 + 32.0
  36         temp_c_2dec = f"{temp_c:.5f}" # https://stackoverflow.com/a/15263885/10850071
  37         #return temp_c, temp_f
  38         return temp_c_2dec
  39
  40
  41 myHostname = socket.gethostname()
  42
  43 while True:
  44     nowTimeIso8601 = strftime("%Y%m%dT%H%M%S%z")
  45     nowTimeUE = strftime("%s")
  46     try:
  47         nowTemp = read_temp()
  48         print(str(nowTimeIso8601) + ',' + str(nowTimeUE) + ',' + str(myHostname) + ',' + str(nowTemp), flush=True) # flush to stdout continuously (e.g. without buffer) https://stackoverflow.com/a/14729823
  49     except Exception as e:
  50         print(str(nowTimeIso8601) + ',' + str(nowTimeUE) + ',' + str(myHostname) + ',' + 'ERROR:' + str(e), flush=True)
  51     finally:
  52         time.sleep(10)