#define sensorpin 34 #define DHTPIN 2 #include <BH1750.h> BH1750 lightMeter; #include <Wire.h> #include <DHT.h> DHT dht(DHTPIN, DHT11); #include<WiFi.h> #include<PubSubClient.h> char* ssid ="17group";//此处需要改成你的wifi名称 const char*password = "hhj20011019"; //你的wifi密码 //以下四行参数勿动 const char*mqttServer = "39.106.6.44"; const int mqttPort =1886; const char*mqttUser = "iotlab"; const char*mqttPassword = "iot20121013"; WiFiClient espClient; PubSubClient client(espClient); char msg[50]; //用于存储向外发送的消息 //回调函数，topic是主题，payload就是收到的信息 void callback(char*topic, byte* payload, unsigned int length) { Serial.print("Messagearrived in topic: "); Serial.println(topic); Serial.print("Message:"); for (int i = 0; i< length; i++) { Serial.print((char)payload[i]); } Serial.println(); Serial.println("-----------------------"); } void setup() { Serial.begin(115200); WiFi.begin(ssid,password); while (WiFi.status()!= WL_CONNECTED) { delay(500); Serial.println("Connectingto WiFi.."); } Serial.println("Connectedto the WiFi network"); client.setServer(mqttServer,mqttPort); client.setCallback(callback); while (!client.connected()){ Serial.println("Connectingto MQTT..."); //请将cs202112345后面的数字替换成自己的学号 if (client.connect("cs225150340",mqttUser, mqttPassword )) { Serial.println("connected"); }else { Serial.print("failedwith state "); Serial.print(client.state()); delay(2000); } } client.subscribe("sub225150340");//请将后面的数字替换成自己的学号 { Serial.begin(115200); // Initialize the I2C bus (BH1750 library doesn't do this automatically) Wire.begin(); // On esp8266 you can select SCL and SDA pins using Wire.begin(D4, D3); // For Wemos / Lolin D1 Mini Pro and the Ambient Light shield use // Wire.begin(D2, D1); lightMeter.begin(); } } void loop() { client.loop();//此句为循环监测是否有消息过来，勿删 //以下是发送一组数据的例子,实际场景替换成读取的传感器数值 float hum = dht.readHumidity(); float temp = dht.readTemperature(); float lux = lightMeter.readLightLevel(); int soilhum =analogRead(sensorpin); snprintf(msg,50,"%.2f,%.2f,%.1f,%d",hum,temp,lux,soildhum); Serial.println(msg); //这行只是为了调试用 client.publish("pub225150430", msg); //请将后面的数字替换成自己的学号 delay(1000); } 如何接收 #define sensorpin 34 int svalue; void setup(){ Serial.begin(9600); } void loop(){ svalue=analogRead(sensorpin); Serial.println(svalue); delay(1000); } 上的数据

您可以使用 MQTT 客户端订阅相应主题，接收通过 MQTT 发布的数据。在代码中，传感器数据通过以下语句发布到 MQTT 主题 "pub225150430" 中：

client.publish("pub225150430", msg);

因此，您可以使用相同的 MQTT 客户端对象 `client`，在回调函数中订阅 "pub225150430" 主题并解析接收到的数据。

以下是示例代码：

#include <PubSubClient.h>

WiFiClient wifiClient;
PubSubClient client(wifiClient);

char receivedMsg[50];

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

void setup() {
  Serial.begin(115200);
  
  // Connect to Wi-Fi network
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Connect to MQTT broker
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);
  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    if (client.connect("cs225150340", mqttUser, mqttPassword)) {
      Serial.println("connected");
    } else {
      Serial.print("failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }

  // Subscribe to "pub225150430" topic
  client.subscribe("pub225150430");
}

void loop() {
  client.loop();

  // Parse received message
  String msgStr = String(receivedMsg);
  float hum, temp, lux;
  int soilhum;
  sscanf(msgStr.c_str(), "%f,%f,%f,%d", &hum, &temp, &lux, &soilhum);
  
  // Do something with received data
  Serial.print("Humidity: ");
  Serial.println(hum);
  Serial.print("Temperature: ");
  Serial.println(temp);
  Serial.print("Lux: ");
  Serial.println(lux);
  Serial.print("Soil Humidity: ");
  Serial.println(soilhum);
  
  delay(1000);
}