1 实验目的

学习ESP32连接阿里云物联网平台并实现相互通信；

2 在阿里云物联网平台添加实验设备

1. 在阿里云物联网平台添加本次实验设备，详细步骤请参考：阿里云物联网平台创建产品与设备

3 ESP32连接阿里云物联网平台

3.1 准备ESP32工程

1. 复制官方例程 examples\protocols\mqtt\tcp

3.2 准备ESP32所需的MQTT相关参数

ESP32使用MQTT协议连接阿里云物联网平台需要用到如下参数：

#define   host       xxx       //或称mqttHostUrl、Broker Address
#define   port       xxx
#define   client_id  xxx
#define   username   xxx
#define   password   xxx
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在阿里云物联网平台查看可查看上诉参数

3.4 ESP32工程主要代码分析

mqtt相关函数详细操作请参考：乐鑫官方说明

/*由阿里网平台可得如下信息*/
// "clientId":"xxxxxFwJvIO.light_02|securemode=2,signmethod=hmacsha256,timestamp=1718174871589|"
// "username":"light_02&xxxxxFwJvIO"
// "mqttHostUrl":"xxxxxFwJvIO.iot-as-mqtt.cn-shanghai.aliyuncs.com"
// "passwd":"xxxxxac7f1796e87ad43fd4dd0ead023d9b8c7e3050a9bae91ab58505dc8a514"
// "port":1883

#define   Aliyun_hostname       "xxxxxFwJvIO.iot-as-mqtt.cn-shanghai.aliyuncs.com" //或称mqttHostUrl、Broker Address
#define   Aliyun_port       1883
#define   Aliyun_client_id  "xxxxxFwJvIO.light_02|securemode=2,signmethod=hmacsha256,timestamp=1718174871589|"
#define   Aliyun_username   "light_02&xxxxxFwJvIO"
#define   Aliyun_password   "xxxxxac7f1796e87ad43fd4dd0ead023d9b8c7e3050a9bae91ab58505dc8a514"

void mqtt_app_start(void)
{
    // 官方例程原程序
    // esp_mqtt_client_config_t mqtt_cfg = {
    //     .broker.address.uri = CONFIG_BROKER_URL,
    // };

    
    esp_mqtt_client_config_t mqtt_cfg = {
        // idf 新版本(esp-idf-V5.2.1)参数配置如下
        .broker.address.transport = MQTT_TRANSPORT_OVER_TCP,
        .broker.address.hostname = Aliyun_hostname,
        .broker.address.port = Aliyun_port,
        .credentials.client_id = Aliyun_client_id,
        .credentials.username = Aliyun_username,
        .credentials.authentication.password = Aliyun_password,

         // idf 旧版本参数配置如下
		// .host = Aliyun_hostname,
		// .port = Aliyun_port,
		// .client_id = Aliyun_client_id,
		// .username = Aliyun_username,
		// .password = Aliyun_password,
    };

    client = esp_mqtt_client_init(&mqtt_cfg);
    esp_mqtt_client_register_event(client, ESP_EVENT_ANY_ID, mqtt_event_handler, client);
    esp_mqtt_client_start(client);
}

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3.5 配置并烧录工程

1. idf.py menuconfig配置wifi
2. 烧录程序

3.6 ESP32连接阿里云物联网验证

1. 通过上诉初始化等操作，给esp32烧录程序复位后，esp32串口数据显示连接成功
   
2. 阿里云物联网平台也显示设备在线
   

4 ESP32与阿里云物联网平台通信

1. 复制如下Topic，
   

2. 在程序中修改如下

#define   AliyunPublishTopic_user_update    "/xxxxxFwJvIO/light_02/user/update"
#define   AliyunSubscribeTopic_user_get     "/xxxxxFwJvIO/light_02/user/get"

static const char mqtt_publish_data3[] = "hello aliyun, i am esp32.i and you connected ok";

static void mqtt_event_handler(void *handler_args, esp_event_base_t base, int32_t event_id, void *event_data)
{
    ESP_LOGD(TAG, "Event dispatched from event loop base=%s, event_id=%" PRIi32 "", base, event_id);
    esp_mqtt_event_handle_t event = event_data;
    esp_mqtt_client_handle_t client = event->client;
    int msg_id;
    switch ((esp_mqtt_event_id_t)event_id) {
    case MQTT_EVENT_CONNECTED:
        ESP_LOGI(TAG, "MQTT_EVENT_CONNECTED");

        //1. 连接成功后发消息到阿里云物联网平台
        msg_id = esp_mqtt_client_publish(client, AliyunPublishTopic_user_update, mqtt_publish_data3, strlen(mqtt_publish_data3), 1, 0);
        ESP_LOGI(TAG, "sent publish successful, msg_id=%d", msg_id);

        //2. 订阅阿里云物联网平台 user get topic
        msg_id = esp_mqtt_client_subscribe(client, AliyunSubscribeTopic_user_get, 0);
        ESP_LOGI(TAG, "execute subscribe event, msg_id=%d", msg_id);

        break;
    case MQTT_EVENT_DISCONNECTED:
        ESP_LOGI(TAG, "MQTT_EVENT_DISCONNECTED");
        break;
    
    case MQTT_EVENT_SUBSCRIBED:
        ESP_LOGI(TAG, "MQTT_EVENT_SUBSCRIBED, msg_id=%d", event->msg_id);
        break;
    case MQTT_EVENT_UNSUBSCRIBED:
        ESP_LOGI(TAG, "MQTT_EVENT_UNSUBSCRIBED, msg_id=%d", event->msg_id);
        break;
    case MQTT_EVENT_PUBLISHED:
        ESP_LOGI(TAG, "MQTT_EVENT_PUBLISHED, msg_id=%d", event->msg_id);
        break;
    case MQTT_EVENT_DATA:
        ESP_LOGI(TAG, "MQTT_EVENT_DATA");
        printf("TOPIC=%.*s\r\n", event->topic_len, event->topic);
        printf("DATA=%.*s\r\n", event->data_len, event->data);
        break;
    case MQTT_EVENT_ERROR:
        break;
    default:
        ESP_LOGI(TAG, "Other event id:%d", event->event_id);
        break;
    }
}
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3. 编译并烧录程序后，阿里云物联网平台数据如下
   
4. 阿里云发数据给esp32