树莓派使用DS18B20模块测量温度

sudo raspi-config
进入interfacingoptions
enable one-wire interface

sudo apt-get update
sudo apt-get upgrade

pi@raspberrypi:~$ cd /sys/bus/w1/devices/
pi@raspberrypi:/sys/bus/w1/devices$ ls
28-00000xxxxxx w1_bus_master1

cd 28-00000xxxxxx
cat w1_slave
显示：
46 01 4b 46 7f ff 0c 10 2f : crc=2f YES
46 01 4b 46 7f ff 0c 10 2f t=20375
第二行的t=20375就是当前的温度值，要换算成摄氏度，除以1000，即当前温度为20375/1000=20.375摄氏度。

#!/usr/bin/python3
import os,time

device_file ='/sys/bus/w1/devices/28-031681e171ff/w1_slave'

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

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
return temp_c

while True:
print('temp C = %f'%read_temp())
time.sleep(1)

pi@raspberrypi:~/myPython $ ./temp_ds18b20.py
temp C = 20.687000
temp C = 20.687000
temp C = 20.687000
temp C = 20.750000
temp C = 20.750000
temp C = 20.750000