ds18b20.py

#!/usr/bin/env python3

from os.path import join, exists
from collections import namedtuple

DS18B20Result = namedtuple("DS18B20Result", ("sensor_name", "is_valid", "temp"))

import os
import glob
import math
import time
import sys

class DS18B20:
	def __init__(self, gpio):
		self.gpio = gpio
		master_map = {16:1,17:2,26:3,27:4}
		master = master_map[gpio]
		
		self.master = master
		self.base_dir=f'/sys/bus/w1/devices/w1_bus_master{master}/'
		self.device_folder = glob.glob(self.base_dir + '28*')[0]
		self.device_file = self.device_folder + '/w1_slave'

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

	def read(self):
		lines = self.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:]
			self.temperature = float(temp_string) / 1000.0
			return DS18B20Result(self.get_sensor_name(), True, self.temperature)
		
	def get_sensor_type_name(self):
		return "DS18B20"
		
	def get_sensor_name(self):
		return "DS18B20_w1_gpio-%i" % (self.gpio)

	def get_sensor_fields(self):
		return ["temp"]
		
if __name__ == "__main__":
	import argparse
	
	parser = argparse.ArgumentParser()

	parser.add_argument('--gpio', type = int, default = 16)
	args = parser.parse_args()
	
	mydevice = DS18B20(args.gpio)
	

	result = mydevice.read()
	print("%s - is_valid:%r temperature:%.2f" % (result.sensor_name,result.is_valid, result.temp))