esp32 mqtt 连接thingsboard 的代码

ESP32连接到ThingsBoard服务器并使用MQTT协议通信的代码示例会在物联网开发中经常遇到。这里是一个基本的步骤：

#include <WiFi.h>
#include <PubSubClient.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqtt_server = "your_THINGSBOARD_HOST";
const int mqtt_port = 1883;
const char* client_id = "esp32_client";
char device_name[] = "esp32_device";

WiFiClient wifiClient;
PubSubClient client(wifiClient);

void connectToWiFi() {
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.println("Connecting to WiFi...");
    }
    Serial.println("Connected to WiFi!");
}

void reconnect() {
    while (!client.connected()) {
        if (client.connect(client_id, device_name)) {
            Serial.println("Connected to MQTT server");
            client.subscribe("$SYS/#"); // Subscribe to system topics
        } else {
            Serial.print("Failed to connect, retrying in 5 seconds...");
            delay(5000);
        }
    }
}

void publishData() {
    String data = "temperature=25, humidity=60"; // Example payload
    client.publish("devices/" + device_name + "/ telemetry", data.c_str());
}

void setup() {
    Serial.begin(115200);
    connectToWiFi();
    client.setServer(mqtt_server, mqtt_port);
    reconnect();
}

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

    publishData(); // Publish your sensor readings here
    client.loop();
}

在这个例子中，你需要替换`ssid`, `password`, 和`mqtt_server`为实际的网络信息。在`loop()`函数中，你可以根据你的硬件设备实时收集数据，并将其发送到ThingsBoard指定的设备主题(`"devices/esp32_device/telemetry"`)。