STM32移植 MQTT

stm32移植mqtt

1. 下载MQTT的库：Paho https://github.com/eclipse/paho.mqtt.embedded-c
2. 将MQTTPacket\src目录下的文件添加到工程
3. MQTTPacket\samples下的transport.c、transport.h添加到工程。

	//接收数据,recv函数仅仅是copy数据，真正的接收数据是协议来完成的）， recv函数返回其实际copy的字节数。
	int transport_getdata(unsigned char* buf, int count)
	{
		int rc = 0;
	  u16 len = 0;
	  u8 *data = 0;
		while(1)
		{ 
			if(UART7_RX_STA&0X8000)		//接收到一次数据了
			{
				memcpy(buf, (void*)&UART7_RX_BUF[read_buf_len], count);
				read_buf_len += count;			
				break;
			}
			delay_ms(10);
		}
		return count;
	} 

####在需要调用的地方实现订阅发布和读取订阅。

	 //打开网络连接
	mysock = transport_open(host, port);
	if(mysock < 0)
		return mysock;
	printf("Sending to hostname %s port %d\n", host, port);
//现在将连接字符串格式化一下，现在还没有发送
	len = MQTTSerialize_connect(buf, buflen, &data);
	printf("%s",buf);
	//现在是数据的发送
	rc = transport_sendPacketBuffer(mysock, buf, len);
	/* 等待connack *///发送后接收服务器返回的数据，这里使用了一个函数的指针，要定义这个指针
	if (MQTTPacket_read(buf, buflen, transport_getdata) == CONNACK)//CONNACK – 确认连接请求
	{
		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;
	/* 订阅 */
	topicString.cstring = "substopic";
	len = MQTTSerialize_subscribe(buf, buflen, 0, msgid, 1, &topicString, &req_qos);
	rc = transport_sendPacketBuffer(mysock, buf, len);
	//等待服务器答复
	//SUBACK 订阅确认 报文包含一个返回码清单， 它们指定了 SUBSCRIBE 请求的每个订阅被授予的最大 QoS 等级。
	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;
	/* 循环获取消息 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 响应报文，当qos>0时才有响应
		{
			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); //消息到达
		}
		printf("publishing reading\n");//读取发布
     //下面两行是用来发布消息。这里发布，上面订阅，就形成了一个循环。
		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);//发送心跳
		rc = transport_sendPacketBuffer(mysock, buf, len);//发送
		delay_s(55);
		printf("心跳");
	}
exit:
	transport_close(mysock); 

MQTT实质上只是一个协议，搞清楚什么是订阅什么是发布，如何保持连接。

鉴于网友要求现在提供工程文件：
链接：https://pan.baidu.com/s/1OiG0CdIuDe_RTRe95zougQ
提取码：d5ni