ESP8266 + DHT11 + OLED0.96温湿度中文显示和MQTT（三）

本文接上文 ESP8266 + DHT11 + OLED0.96温湿度中文显示和MQTT（二）-优快云博客

本章节主要接上节，增加MQTT发送数据，硬件参数，和接线，请看上文

增加代码步骤如下：

1）  引入MQTT头文件和mqtt的参数变量

#include <PubSubClient.h>


const char* mqtt_server = "192.168.1.10"; //这里换上你自己的MQTT的服务器IP
const char* mqtt_username = "admin";
const char* mqtt_password = "admin";
const int mqtt_port = 1883;
const char* mqtt_client_id = "d13U1IZPW0VB&107";
const char* mqtt_sensor_topic = "dht11";
unsigned long last_send = 0;

PubSubClient mqttClient(espClient); //声明mqtt客户端

2）编写MQTT 连接函数

void mqttReconnect() {
  // Loop until we're reconnected
  while (!mqttClient.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (mqttClient.connect(mqtt_client_id, mqtt_username, mqtt_password)) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(mqttClient.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

3）在setup函数的  connectWifi();语句后增加

    mqttClient.setServer(mqtt_server, mqtt_port);

4） 增加温湿度数据发送函数

void handleTemperatureAndHumidity(float t,float h) {
  if (isnan(h) || isnan(t) ) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }
  // 准备JSON Payload
  String payload = "[";
  
  payload += "{";
  payload += "\"id\":\"temperature\","; 
  payload += "\"value\":"; 
  payload += t; payload += "},";

  payload += "{";
  payload += "\"id\":\"humidity\","; 
  payload += "\"value\":"; 
  payload += h; payload += "}";
  
  payload += "]";
  
  // 发送温湿度数据
  char attributes[100];
  payload.toCharArray( attributes, 100 );
  mqttClient.publish( mqtt_sensor_topic, attributes );
  Serial.println( attributes );
}

5）在loop函数结尾里增加

  if ( !mqttClient.connected() ) { // MQTT 是否连接成功
    mqttReconnect();
  }

  if ( millis() - last_send > 5000 ) { // 每5秒发布一次温湿度数据
    handleTemperatureAndHumidity(temperature,humidity);
    last_send = millis();
  }
  mqttClient.loop();

6） 编译，上传代码，执行打开串口监视器，显示发送成功

7）打开MQTT客户端，我们订阅topic 为 dht11的主题 则发现可以正常接收数据

至此基于 ESP8266 + DHT11 + OLED0.96温湿度中文显示和MQTT数据传输就介绍完了，感谢大家