ESP8266 RTOS學習之旅（5）— MQTT通信

ESP8266 RTOS學習之旅（5）— MQTT通信

一、前言

在上一節：ESP8266 RTOS學習之旅（4）— UDP通信和TCP客戶端通信 的基礎上，將ESP8266_RTOS_SDK-2.0.0\examples\mqtt_demo\下出去user_main.c的文件複製到app目錄下（提示覆蓋則確認）。
因爲RTOS 2.0.0對MQTT的支持好像有問題，所以我拉取v2.1.1版本的代碼下來使用，樂鑫官方的倉庫：

git clone -b v2.1.1 https://github.com/espressif/ESP8266_RTOS_SDK.git

然後因爲github不穩定，特別是網速不夠的話經常出問題，所以我複製了一份代碼到gitee上：

git clone -b v2.1.1 https://gitee.com/william_william/ESP8266_RTOS_SDK.git

二、開始MQTT通信

還有一個問題就是，MQTT不支持斷線重連，所以我只好每隔5s發佈一個主題，當發佈不成功時，重新連接MQTT。編寫app_main.c文件如下：

#include "esp_common.h"

#if !defined(MQTT_TASK)
#define MQTT_TASK
#endif

#include "lwip/sockets.h"
#include "mqtt/MQTTClient.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

static void messageArrived(MessageData* data)
{
    printf("topic Message arrived: \n%s\n", data->message->payload);
}

/* 1、定義一個MQTT客戶端結構體 */
MQTTClient client;
/* 2、網絡連接參數結構體 */
Network network;
/* 3、MQTT連接參數結構體 */
MQTTPacket_connectData connectData = MQTTPacket_connectData_initializer;
unsigned char sendbuf[80], readbuf[80] = {0};
int count = 0;
MQTTMessage message;
char payload[30];

void mqtt_connect(void)
{
	/* 4、連接到mqtt服務器 */
	int rc = NetworkConnect(&network, "39.96.35.207", 1883);
	if (rc!= 0)	{
		printf("Return code from network connect is %d\n", rc);
	}

#if defined(MQTT_TASK)

    if ((rc = MQTTStartTask(&client)) != pdPASS) {
        printf("Return code from start tasks is %d\n", rc);
    } else {
        printf("Use MQTTStartTask\n");
    }

#endif

	/* 5、設置MQTT連接參數 */
	connectData.MQTTVersion = 3;
	connectData.clientID.cstring = "ESP8266";	/* clientID */
	connectData.username.cstring = "ESP8266";	/* 用戶名 */
	connectData.password.cstring = "123456";	/* 用戶名密碼 */

	/* 6、向mqtt服務器發送連接報文 */
	rc = MQTTConnect(&client, &connectData);
	if (rc != 0) {
		printf("Return code from MQTT connect is %d\n", rc);
	} else {
		printf("MQTT Connected\n");
	}

	/* 7、訂閱一個主題 ，並設置訂閱主題回調函數 */
	rc = MQTTSubscribe(&client, "ESP8266_Subscribe", QOS0, messageArrived);
	if (rc != 0) {
		printf("Return code from MQTT subscribe is %d\n", rc);
	} else {
		printf("MQTT subscribe to topic ESP8266_Subscribe OK\n");
	}
}

int app_main(void)
{
	int rc = 0;
	client.defaultMessageHandler = messageArrived;
	NetworkInit(&network);
	MQTTClientInit(&client, &network, 30000, sendbuf, sizeof(sendbuf), readbuf, sizeof(readbuf));

    while(1)
    {
        message.qos = QOS0;
        message.retained = 0;
        message.payload = payload;
        sprintf(payload, "message number %d", count);
        message.payloadlen = strlen(payload);

        if ((rc = MQTTPublish(&client, "ESP8266_Publish", &message)) != 0) {
            printf("Return code from MQTT publish is %d\n", rc);
            mqtt_connect();
        } else {
            printf("MQTT publish topic ESP8266_Publish ok, message number is %d\n", count++);
        }

        vTaskDelay(5000 / portTICK_RATE_MS);  //send every 1 seconds
    }


    return 0;
}

編譯下載運行，可以看到，連接MQTT服務器成功，訂閱和發佈主題也沒問題

打開EMQ的控制檯，可以看到，其連接成功

接收到了其發佈的主題