Arduino esp8266实现把温湿度传感数据传到MQTT客户端

一、MQTT环境搭建

1. 安装MQTT Broker: mosquitto
2. 安装mqtt.fx 详情见该文章：https://blog.youkuaiyun.com/Mculover666/article/details/103799033
3. 测试是否安装成功：
   注意Broker Address，我这里使用的是官方的测试服务器，Client ID根据需要自行设置
   
   设置两个不同的Client ID和Profile Name 看能否实现订阅和发送功能：
   
   如图，设置主题为日期，test1发布，test2订阅，成功收到了hello world的信息，说明环境配置成功

二、将开发板连上WIFI和MQTT客户端

1.开发板连入WIFI

1. 需要安装的库：
2. 需要的头文件和全局变量：

#include <ESP8266WiFi.h>
const char* ssid = "";  //WIFI名
const char* password = ""; //WiFi密码

3. setup函数中设置

  setup_wifi();

4. setup_wifi函数体

void setup_wifi() {

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

5. 完整连WiFi程序

#include <ESP8266WiFi.h>
const char* ssid = "";  //WIFI名 根据自己情况输入
const char* password = ""; //WiFi密码 根据自己情况输入
void setup() {
  Serial.begin(115200);  //必备
   setup_wifi();
}

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop() {}

• 观察上板子的结果
  

2.在连WIFI基础上连上MQTT

1. 用到的库
   
2. 用到的头文件和配置

#include <PubSubClient.h>
const char* mqtt_server = "your address";  //mqtt服务器地址
WiFiClient espClient;
PubSubClient client(espClient);

3. setup函数中配置

  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

4. 用到的其他函数

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("Your Client ID")) 
    {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("Your Topic", "The message you want to publish"); //在给定主题下发布信息
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

5. 完整的连WIFI，连MQTT程序：

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "";  //WIFI名
const char* password = ""; //WiFi密码
const char* mqtt_server = "";  //mqtt服务器地址


WiFiClient espClient;
PubSubClient client(espClient);


void setup() {
  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void setup_wifi() {

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) 
{
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("")) //Client ID
    {
      Serial.println("connected");
      // Once connected, publish an announcement...
      client.publish("your topic", "the message you want to send"); //在给定的主题发布给定的消息
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}
void loop() {

  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  delay(2000);
}

6. 运行结果：
   
   至此，完成了esp8266和MQTT客户端之间的连接，并实现了信息的发送

三、将温湿度数据通过MQTT传到客户端

1. 用到的库
   
2. 用到的头文件和配置

#include "DHT.h"
#define DHTPIN 5
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE, 15);

3. 在loop函数当中实现对温湿度数据的处理和发送

float h = dht.readHumidity();
float t = dht.readTemperature();
char c[50];
String data ="温度："+String(t) +"℃"+","+"湿度："+ String(h)+"%" ; //生成要传输的数据
strcpy(c,data.c_str());
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  long now = millis();
  if (now - lastMsg > 2000) //一点时间间隔
  {
    lastMsg = now;
    ++value;
    snprintf (msg, 75, c, value);
    Serial.print("Publish message: ");
    Serial.println(msg);
    client.publish("ouTopic", msg);
  }

4. 整体运行结果
   
   

总结

操作并不是很困难，主要是Arduino各种库和函数的使用，希望对读者有帮助。