本教程中，您将学习如何在NodeMCU上使用DHT11温湿度传感器。并了解温湿度传感器的工作原理，以及如何通过串口监视器查看传感器读取的数值。

设备清单

  • NodeMCU开发板一块
  • DHT11温湿度传感器一个

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(DHT11模块)

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(NodeMcu板子)
DHT11是通过测量两个电极之间的电阻来检测水蒸汽的。湿度检测部件表面有电极的保湿基板。

当水蒸气被基板吸收时，离子被基板释放，这个过程将会增加电极之间的导电性。

两个电极之间的电阻变化与相对湿度成比例。

较高的相对湿度会降低电极之间的电阻，而较低的相对湿度会增加电极之间的电阻。

如何在NodeMCU上连接DHT11

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将DHT11连接到NodeMCU是比较简单的，但连接方式有所不同，具体取决于您使用的是3个引脚的传感器还是4个引脚的传感器。

连接方式如下：

DHT11上标有（+或VCC）引脚的连接nodemcu的+ 3V引脚。

DHT11上标有（S或OUT）引脚的连接nodemcu的D4V引脚。

DHT11上标有（-或GND）引脚的连接nodemcu的GND引脚。

代码如下

#include <SimpleDHT.h>

// for DHT11, 
//      VCC: 5V or 3V
//      GND: GND
//      DATA: 2
int pinDHT11 = 2;
SimpleDHT11 dht11(pinDHT11);

void setup() {
  Serial.begin(115200);
}

void loop() {
  // start working...
  Serial.println("=================================");
  Serial.println("Sample DHT11...");
  
  // read without samples.
  byte temperature = 0;
  byte humidity = 0;
  int err = SimpleDHTErrSuccess;
  if ((err = dht11.read(&temperature, &humidity, NULL)) != SimpleDHTErrSuccess) {
    Serial.print("Read DHT11 failed, err="); Serial.println(err);delay(1000);
    return;
  }
  
  Serial.print("Sample OK: ");
  Serial.print((int)temperature); Serial.print(" *C, "); 
  Serial.print((int)humidity); Serial.println(" H");
  
  // DHT11 sampling rate is 1HZ.
  delay(1500);
}

使用演示

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DHT11+WEB版

我们先看看效果
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将DHT11的数据通过web服务器反馈过来。

开发思路

我们首先要安装两个库DHT和Adafruit Unified Sensor
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代码如下：

#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include "DHT.h"

// Uncomment one of the lines below for whatever DHT sensor type you're using!
#define DHTTYPE DHT11   // DHT 11
//#define DHTTYPE DHT21   // DHT 21 (AM2301)
//#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321

/*Put your SSID & Password*/
const char* ssid = "kali";  // Enter SSID here
const char* password = "12345678900";  //Enter Password here

ESP8266WebServer server(80);

// DHT Sensor
uint8_t DHTPin = D4; 
               
// Initialize DHT sensor.
DHT dht(DHTPin, DHTTYPE);                

float Temperature;
float Humidity;
 
void setup() {
  Serial.begin(115200);
  delay(100);
  
  pinMode(DHTPin, INPUT);

  dht.begin();              

  Serial.println("Connecting to ");
  Serial.println(ssid);

  //connect to your local wi-fi network
  WiFi.begin(ssid, password);

  //check wi-fi is connected to wi-fi network
  while (WiFi.status() != WL_CONNECTED) {
  delay(1000);
  Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected..!");
  Serial.print("Got IP: ");  Serial.println(WiFi.localIP());

  server.on("/", handle_OnConnect);
  server.onNotFound(handle_NotFound);

  server.begin();
  Serial.println("HTTP server started");

}
void loop() {
  
  server.handleClient();
  
}

void handle_OnConnect() {

 Temperature = dht.readTemperature(); // Gets the values of the temperature
  Humidity = dht.readHumidity(); // Gets the values of the humidity 
  server.send(200, "text/html", SendHTML(Temperature,Humidity)); 
}

void handle_NotFound(){
  server.send(404, "text/plain", "Not found");
}

String SendHTML(float Temperaturestat,float Humiditystat){
  String ptr = "<!DOCTYPE html> <html>\n";
  ptr +="<head> <meta name=\"viewport\" content=\"width=device-width,  initial-scale=1.0, user-scalable=no\">\n";
  ptr +="<link href=\"https://fonts.googleapis.com/css?family=Open+Sans:300,400,600\" rel=\"stylesheet\">\n";
  ptr +="<meta charset=\"UTF-8\">\n";
  ptr +="<title>Priess的小窝—智能温湿计</title>\n";
  ptr +="<style>html { font-family: 'Open Sans', sans-serif; display: block; margin: 0px auto; text-align: center;color: #333333;}\n";
  ptr +="body{margin-top: 50px;}\n";
  ptr +="h1 {margin: 50px auto 30px;}\n";
  ptr +=" .wd {margin: 50px auto 30px;width: auto;color: #f39c12}\n";
  ptr +=" .wd1 {margin: 50px auto 30px;width: auto;color: #3498db}\n";
  ptr +=".side-by-side{display: inline-block;vertical-align: middle;position: relative;}\n";
  ptr +=".humidity-icon{background-color: #3498db;width: 30px;height: 30px;border-radius: 50%;line-height: 36px;}\n";
  ptr +=".humidity-text{font-weight: 600;padding-left: 15px;font-size: 19px;width: 160px;text-align: left;}\n";
  ptr +=".humidity{font-weight: 300;font-size: 60px;color: #3498db;}\n";
  ptr +=".temperature-icon{background-color: #f39c12;width: 30px;height: 30px;border-radius: 50%;line-height: 40px;}\n";
  ptr +=".temperature-text{font-weight: 600;padding-left: 15px;font-size: 19px;width: 160px;text-align: left;}\n";
  ptr +=".temperature{font-weight: 300;font-size: 60px;color: #f39c12;}\n";
  ptr +=".superscript{font-size: 17px;font-weight: 600;position: absolute;right: -20px;top: 15px;}\n";
  ptr +=".data{padding: 10px;}\n";
  ptr +="</style>\n";
  ptr +="</head>\n";
  ptr +="<body>\n";
  
   ptr +="<div id=\"webpage\">\n";
   
   ptr +="<h1>室内温室检测系统</h1>\n";
   ptr +="<div class=\"data\">\n";
   ptr +="<div class=\"side-by-side temperature-icon\">\n";
   ptr +="<svg version=\"1.1\" id=\"Layer_1\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" x=\"0px\" y=\"0px\"\n";
   ptr +="width=\"9.915px\" height=\"22px\" viewBox=\"0 0 9.915 22\" enable-background=\"new 0 0 9.915 22\" xml:space=\"preserve\">\n";
   ptr +="<path fill=\"#FFFFFF\" d=\"M3.498,0.53c0.377-0.331,0.877-0.501,1.374-0.527C5.697-0.04,6.522,0.421,6.924,1.142\n";
   ptr +="c0.237,0.399,0.315,0.871,0.311,1.33C7.229,5.856,7.245,9.24,7.227,12.625c1.019,0.539,1.855,1.424,2.301,2.491\n";
   ptr +="c0.491,1.163,0.518,2.514,0.062,3.693c-0.414,1.102-1.24,2.038-2.276,2.594c-1.056,0.583-2.331,0.743-3.501,0.463\n";
   ptr +="c-1.417-0.323-2.659-1.314-3.3-2.617C0.014,18.26-0.115,17.104,0.1,16.022c0.296-1.443,1.274-2.717,2.58-3.394\n";
   ptr +="c0.013-3.44,0-6.881,0.007-10.322C2.674,1.634,2.974,0.955,3.498,0.53z\"/>\n";
   ptr +="</svg>\n";
   ptr +="</div>\n";
   ptr +="<div class=\"side-by-side temperature-text\">室内温度：</div>\n";
   ptr +="<div class=\"side-by-side temperature\">";
   ptr +=(int)Temperaturestat;
   ptr +="<span class=\"superscript\">°C</span></div>\n";
   ptr +="</div>\n";
   ptr +="<div class=\"data\">\n";
   ptr +="<div class=\"side-by-side humidity-icon\">\n";
   ptr +="<svg version=\"1.1\" id=\"Layer_2\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" x=\"0px\" y=\"0px\"\n\"; width=\"12px\" height=\"17.955px\" viewBox=\"0 0 13 17.955\" enable-background=\"new 0 0 13 17.955\" xml:space=\"preserve\">\n";
   ptr +="<path fill=\"#FFFFFF\" d=\"M1.819,6.217C3.139,4.064,6.5,0,6.5,0s3.363,4.064,4.681,6.217c1.793,2.926,2.133,5.05,1.571,7.057\n";
   ptr +="c-0.438,1.574-2.264,4.681-6.252,4.681c-3.988,0-5.813-3.107-6.252-4.681C-0.313,11.267,0.026,9.143,1.819,6.217\"></path>\n";
   ptr +="</svg>\n";
   ptr +="</div>\n";
   ptr +="<div class=\"side-by-side humidity-text\">室内湿度：</div>\n";
   ptr +="<div class=\"side-by-side humidity\">";
   ptr +=(int)Humiditystat;
   ptr +="<span class=\"superscript\">%</span></div>\n";
   ptr +="</div>\n";
   //定义温度变量，并且赋值，用于逻辑判断。
    int wd = Temperaturestat ;
     
   if (wd>=30){
    ptr +="<div class=\"wd\">Hi~ 宝贝今天天气贼热，注入防暑哦！</div>\n";
   }
   if (29>=wd&&wd>20){
    ptr +="<div class=\"wd1\">Hi~ 宝贝今天天气不错吆，尽情的玩耍吧！</div>\n";
   }
   if (wd<10){
    ptr +="<div class=\"side-by-side humidity-text\">Hi~ 宝贝今天天气比较冷，多穿点衣服，小心着凉！</div>\n";
   }
  ptr +="</div>\n";
  ptr +="</body>\n";
  ptr +="</html>\n";
  return ptr;
}

我在源代码的基础上，添加了温馨提示！当温度为不同的范围，提示不同的问候语。

//定义温度变量，并且赋值，用于逻辑判断。
    int wd = Temperaturestat ;
     
   if (wd>=30){
    ptr +="<div class=\"wd\">Hi~ 宝贝今天天气贼热，注入防暑哦！</div>\n";
   }
   if (29>=wd&&wd>10){
    ptr +="<div class=\"wd1\">Hi~ 宝贝今天天气不错吆，尽情的玩耍吧！</div>\n";
   }
   if (wd=<10){
    ptr +="<div class=\"side-by-side humidity-text\">Hi~ 宝贝今天天气比较冷，多穿点衣服，小心着凉！</div>\n";
   }

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Last modification：July 12, 2019
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