文章目录

前言

前言

本文将介绍如何使用ESP32开发板通过MQTT协议连接阿里云物联网平台，并实现消息的发布与订阅功能。我们将使用Arduino IDE进行开发，并借助PubSubClient库实现MQTT通信。

一、准备工作

• ESP32开发板

• Arduino IDE

• 阿里云物联网平台账号

• PubSubClient库

二、阿里云平台配置

1. 登录阿里云物联网平台

2. 创建产品与设备，获取设备三元组（ProductKey、DeviceName、DeviceSecret）

3. 配置Topic，例如：

• 发布Topic: /a1xxxxxx/${deviceName}/user/update

• 订阅Topic: /a1xxxxxx/${deviceName}/user/get

 三、代码实现

#include <WiFi.h>
#include <PubSubClient.h>// WiFi配置
const char* ssid = "your_wifi_ssid";
const char* password = "your_wifi_password";// 阿里云MQTT配置
const char* mqtt_server = "iot-xxxxxx.mqtt.aliyuncs.com";
const int mqtt_port = 1883;
const char* mqtt_clientId = "your_client_id";
const char* mqtt_username = "your_device_name&your_product_key";
const char* mqtt_password = "your_device_secret";WiFiClient espClient;
PubSubClient client(espClient);void setup_wifi() {delay(10);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() {while (!client.connected()) {Serial.print("Attempting MQTT connection...");if (client.connect(mqtt_clientId, mqtt_username, mqtt_password)) {Serial.println("connected");client.subscribe("/a1xxxxxx/${deviceName}/user/get");} else {Serial.print("failed, rc=");Serial.print(client.state());Serial.println(" try again in 5 seconds");delay(5000);}}
}void setup() {Serial.begin(115200);setup_wifi();client.setServer(mqtt_server, mqtt_port);client.setCallback(callback);
}void loop() {if (!client.connected()) {reconnect();}client.loop();// 发布消息示例static unsigned long lastMsg = 0;if (millis() - lastMsg > 5000) {lastMsg = millis();String msg = "Hello from ESP32";client.publish("/a1xxxxxx/${deviceName}/user/update", msg.c_str());Serial.println("Message published");}
}

其中，setup_wifi()用于连接WiFi网络，callback()用于处理接收到的MQTT消息，reconnect()用于处理MQTT连接与重连。

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总结

通过本文，能够成功实现了ESP32与阿里云物联网平台的MQTT通信。