传感器的使用——DH11的使用方法

使用DH11先把上面的圆柱盖先拿开后，可以看到接线方法，如 ACC、OUT、GND。另外板子上还有二个插口，分别可用于 光敏电阻 和 热敏电阻，可以扩展自己的功能。

要使用DH11需要先下载DH11的函数库，打开Arduino后，管理库，在搜索 DH11 即可搜索到 DHT_sensor_library，打开示例 DHTtester ，编译上传，会发现一个错误，大致意思是缺少 Adafruit_Sensor.h 这个头文件，可在 https://github.com/adafruit/Adafruit_Sensor 此处下载，将下载后的压缩包解压后，找到 Adafruit_Sensor.h 文件，复制到 库文件夹 DHT_sensor_library 下即可，重新打开 Arduino后，编译就没有错误了，上传之后可以看到 湿度，C温度，F温度，体感C温度，体感F温度。

示例代码如下：

// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain

// 导入头文件
#include "DHT.h"
// 定义OUT接口的数字引脚
#define DHTPIN 2     // what digital pin we're connected to

// Uncomment whatever type you're using!
// 选择DHT类型为 DHT 11
#define DHTTYPE DHT11   // DHT 11
//#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor.
// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors.  This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster procs.
// 生成 DHT 对象，参数是PIN和DHT类型
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  Serial.println("DHTxx test!");

  // 必须使用的begin()函数  
  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  // 每次等待2秒后再输出（这里必须等大于1秒，不然不准确）
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  // readHumidity() 这里是读取当前的湿度
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  // readTemperature() 读取当前的温度，单位C
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  //readTemperature(true) 读取当前的温度，单位F
  float f = dht.readTemperature(true);
  // 如果读取失败则退出，再读取一次
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Compute heat index in Fahrenheit (the default)
  // 读取体感温度，单位F
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  // 读取体感温度，单位C
  float hic = dht.computeHeatIndex(t, h, false);

  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F\t");
  Serial.print("Heat index: ");
  Serial.print(hic);
  Serial.print(" *C ");
  Serial.print(hif);
  Serial.println(" *F");
}