Flask Server for Temperature Sensor and Binary Temperature Threshold Sensor

rest_temp.py

# Use this along with Home Assistant's RESTful Sensor Platform (https://home-assistant.io/components/sensor.rest/)
# to create a temperature sensor using a Raspberry Pi and a DS18B20 probe.
#
# In my case this was being used in a sauna (using a waterproof probe https://www.sparkfun.com/products/11050)
# so I also wanted a binary sensor that indicated whether the temperature had reached a certain threshold or not.

import os
import glob
import time

from flask import Flask, Response, json

app = Flask(__name__)

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

base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'

@app.route("/temp")
def read_temp():
    lines = read_temp_raw()
    while lines[0].strip()[-3:] != 'YES':
        time.sleep(0.2)
        lines = read_temp_raw()
    equals_pos = lines[1].find('t=')
    if equals_pos != -1:
        temp_string = lines[1][equals_pos+2:]
        temp_c = float(temp_string) / 1000.0
        temp_f = temp_c * 9.0 / 5.0 + 32.0
        d = {'temp_c': temp_c, 'temp_f': temp_f, 'hot': ('true' if temp_f>160 else 'false')}
        return Response(json.dumps(d), mimetype='application/json')

        
def read_temp_raw():
    f = open(device_file, 'r')
    lines = f.readlines()
    f.close()
    return lines

app.run(host='0.0.0.0')