基于stm32和esp8266采用mqtt方式连接华为云代码

下面是基于STM32和ESP8266采用MQTT方式连接华为云的代码：

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <SoftwareSerial.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define WIFI_SSID "your_wifi_ssid"
#define WIFI_PASSWORD "your_wifi_password"
#define MQTT_SERVER "your_mqtt_server"
#define MQTT_PORT 1883
#define MQTT_USERNAME "your_mqtt_username"
#define MQTT_PASSWORD "your_mqtt_password"
#define MQTT_TOPIC "your_mqtt_topic"

SoftwareSerial espSerial(2, 3); // RX, TX
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(115200);
  espSerial.begin(115200);
  lcd.begin();
  lcd.backlight();
  lcd.print("Connecting to WiFi");
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    lcd.setCursor(0, 1);
    lcd.print(".");
  }
  lcd.clear();
  lcd.print("WiFi Connected");
  mqttClient.setServer(MQTT_SERVER, MQTT_PORT);
  mqttClient.setCallback(mqttCallback);
}

void loop() {
  if (!mqttClient.connected()) {
    mqttReconnect();
  }
  mqttClient.loop();
  String temp = readTemperature();
  mqttClient.publish(MQTT_TOPIC, temp.c_str());
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(temp);
  delay(1000);
}

void mqttReconnect() {
  while (!mqttClient.connected()) {
    Serial.println("Connecting to MQTT broker...");
    if (mqttClient.connect("ESP8266", MQTT_USERNAME, MQTT_PASSWORD)) {
      Serial.println("MQTT connected");
      mqttClient.subscribe(MQTT_TOPIC);
    } else {
      Serial.print("MQTT connection failed, rc=");
      Serial.print(mqttClient.state());
      Serial.println(" retrying in 5 seconds");
      delay(5000);
    }
  }
}

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

String readTemperature() {
  String temp;
  espSerial.println("AT+CIPSTART=\"TCP\",\"api.openweathermap.org\",80");
  if (espSerial.find("OK")) {
    Serial.println("TCP connection established");
    String request = "GET /data/2.5/weather?q=London,uk&APPID=your_api_key HTTP/1.1\r\nHost: api.openweathermap.org\r\nConnection: close\r\n\r\n";
    espSerial.print("AT+CIPSEND=");
    espSerial.println(request.length());
    if (espSerial.find(">")) {
      Serial.println("Sending request");
      espSerial.print(request);
      if (espSerial.find("CLOSED")) {
        Serial.println("TCP connection closed");
      } else {
        Serial.println("Error closing TCP connection");
      }
    } else {
      Serial.println("Error sending request");
    }
  } else {
    Serial.println("Error establishing TCP connection");
  }
  return temp;
}

这段代码连接到Wi-Fi并建立MQTT连接，然后每秒钟读取温度并将其发布到MQTT主题“your_mqtt_topic”中。当接收到来自MQTT主题的消息时，它将在串行监视器中打印出来。请注意，您需要将代码中的"WIFI_SSID"，"WIFI_PASSWORD"，"MQTT_SERVER"，"MQTT_USERNAME"，"MQTT_PASSWORD"和"MQTT_TOPIC"替换为您自己的值。也需要更改“readTemperature”函数中的API密钥和查询参数，以获取您所需的实际温度值。