STM32 移植MQTT

stm32移植mqtt

1. 下載MQTT的庫：Paho https://github.com/eclipse/paho.mqtt.embedded-c

 

 

• 將MQTTPacket\src目錄下的文件添加到工程
• MQTTPacket\samples下的transport.c、transport.h添加到工程

    //接收數據,recv函數僅僅是copy數據，真正的接收數據是協議來完成的）， recv函數返回其實際copy的字節數。
    int transport_getdata(unsigned char* buf, int count)
    {
        int rc = 0;
      u16 len = 0;
      u8 *data = 0;
        while(1)
        {
            if(UART7_RX_STA&0X8000)     //接收到一次數據了
            {
                memcpy(buf, (void*)&UART7_RX_BUF[read_buf_len], count);
                read_buf_len += count;          
                break;
            }
            delay_ms(10);
        }
        return count;
    }

在需要調用的地方實現訂閱發佈和讀取訂閱。

     //打開網絡連接
    mysock = transport_open(host, port);
    if(mysock < 0)
        return mysock;
    printf("Sending to hostname %s port %d\n", host, port);
//現在將連接字符串格式化一下，現在還沒有發送
    len = MQTTSerialize_connect(buf, buflen, &data);
    printf("%s",buf);
    //現在是數據的發送
    rc = transport_sendPacketBuffer(mysock, buf, len);
    /* 等待connack *///發送後接收服務器返回的數據，這裏使用了一個函數的指針，要定義這個指針
    if (MQTTPacket_read(buf, buflen, transport_getdata) == CONNACK)//CONNACK – 確認連接請求
    {
        unsigned char sessionPresent, connack_rc
        if (MQTTDeserialize_connack(&sessionPresent, &connack_rc, buf, buflen) != 1 || connack_rc != 0)
        {
            printf("Unable to connect, return code %d\n", connack_rc);
            goto exit;
        }
    }
    else
        goto exit;
    /* 訂閱 */
    topicString.cstring = "substopic";
    len = MQTTSerialize_subscribe(buf, buflen, 0, msgid, 1, &topicString, &req_qos);
    rc = transport_sendPacketBuffer(mysock, buf, len);
    //等待服務器答覆
    //SUBACK 訂閱確認 報文包含一個返回碼清單， 它們指定了 SUBSCRIBE 請求的每個訂閱被授予的最大 QoS 等級。
    if (MQTTPacket_read(buf, buflen, transport_getdata) == SUBACK)  /* 等待 suback */
    {
        unsigned short submsgid;
        int subcount;
        int granted_qos;
        rc = MQTTDeserialize_suback(&submsgid, 1, &subcount, &granted_qos, buf, buflen);
        if (granted_qos != 0)
        {
            printf("granted qos != 0, %d\n", granted_qos);
            goto exit;
        }
    }
    else
        goto exit;
    /* 循環獲取消息 on subscribed topic */
//  topicString.cstring = "pubtopic";
//  while (1)
    {
        /* transport_getdata() has a built-in 1 second timeout,
        your mileage will vary */
        if (MQTTPacket_read(buf, buflen, transport_getdata) == PUBLISH)//qos 響應報文，當qos>0時纔有響應
        {
            unsigned char dup;
            int qos;
            unsigned char retained;
            unsigned short msgid;
            int payloadlen_in;
            unsigned char* payload_in;
            int rc;
            MQTTString receivedTopic;
            rc = MQTTDeserialize_publish(&dup, &qos, &retained, &msgid, &receivedTopic,
                    &payload_in, &payloadlen_in, buf, buflen);
            printf("message arrived %.*s\n", payloadlen_in, payload_in); //消息到達
        }
        printf("publishing reading\n");//讀取發佈
     //下面兩行是用來發布消息。這裏發佈，上面訂閱，就形成了一個循環。
        len = MQTTSerialize_publish(buf, buflen, 0, 0, 0, 0, topicString, (unsigned char*)payload, payloadlen);
        rc = transport_sendPacketBuffer(mysock, buf, len);
        delay_ms(1000);
    }
    while(1)
    {
        len = MQTTSerialize_pingreq(buf, buflen);//發送心跳
        rc = transport_sendPacketBuffer(mysock, buf, len);//發送
        delay_s(55);
        printf("心跳");
    }
exit:
    transport_close(mysock);