Raspberry Pi开发之旅-空气温湿度检测（DHT11）

一、首先，简单介绍下DHT11:

DHT11是一个温湿度传感器，分为3个接口，分别为：VCC, DATA, GND

1	VCC	电源	+级，输入3V-5.5V
2	DATA	数据输出	输出引脚
3	GND	接地	接地引脚

之前看网上说，需要在DHT11VCC和DATA之间加一个电阻，经试验完全不需要。

二、引脚连接：

1.VCC接上3V，可以选择1口或者17口

2.DATA接上GPIO口，我选的是GPIO4，第7口

3.GND接上接地口，我选的是第14口

三、Python获取温湿度：

#!/usr/bin/python

import RPi.GPIO as GPIO

import time

channel =4

data = []

j = 0

GPIO.setmode(GPIO.BCM)

time.sleep(1)

GPIO.setup(channel, GPIO.OUT)

GPIO.output(channel, GPIO.LOW)

time.sleep(0.02)

GPIO.output(channel, GPIO.HIGH)

GPIO.setup(channel, GPIO.IN)

while GPIO.input(channel) == GPIO.LOW:

  continue

while GPIO.input(channel) == GPIO.HIGH:

  continue

while j < 40:

  k = 0

  while GPIO.input(channel) == GPIO.LOW:

    continue

  while GPIO.input(channel) == GPIO.HIGH:

    k += 1

    if k > 100:

      break

  if k < 8:

    data.append(0)

  else:

    data.append(1)

  j += 1

print "sensor is working."

print data

humidity_bit = data[0:8]

humidity_point_bit = data[8:16]

temperature_bit = data[16:24]

temperature_point_bit = data[24:32]

check_bit = data[32:40]

humidity = 0

humidity_point = 0

temperature = 0

temperature_point = 0

check = 0

for i in range(8):

  humidity += humidity_bit[i] * 2 ** (7-i)

  humidity_point += humidity_point_bit[i] * 2 ** (7-i)

  temperature += temperature_bit[i] * 2 ** (7-i)

  temperature_point += temperature_point_bit[i] * 2 ** (7-i)

  check += check_bit[i] * 2 ** (7-i)

tmp = humidity + humidity_point + temperature + temperature_point

if check == tmp:

  print "temperature :", temperature, "*C, humidity :", humidity, "%"

else:

  print "wrong"

  print "temperature :", temperature, "*C, humidity :", humidity, "% check :", check, ", tmp :", tmp

GPIO.cleanup()

四、展示结果：

root@raspberrypi:/data/basedata# python/dht11.py

sensor is working.

[0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 0]

temperature : 23 *C, humidity : 93 %

为了测试结果是否准确，我把手指放到传感器上，测试的数据为：

root@raspberrypi:/data/basedata/python# python dht11.py

sensor is working.

[0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1]

temperature : 36 *C, humidity : 95 %

测试无误～

PS: 如果你用的是DS18B20，需要做以下动作：

root@raspberrypi:/# apt-get update

root@raspberrypi:/# apt-get upgrade #更新内核

root@raspberrypi:/# reboot

root@raspberrypi:/# vi /boot/config.txt #在最后一行手动添加：dtoverlay=w1-gpio-pullup,gpiopin=4 来支持新系统读取w1总线设备

root@raspberrypi:/# modprobe w1-gpio #确认设备是否生效

root@raspberrypi:/# modprobe w1-therm

root@raspberrypi:/# cd /sys/bus/w1/devices/