c语言 IOT模型示例

在C语言中，物联网（IoT）模型通常涉及传感器数据的采集、数据处理以及与云平台的通信。以下是一个简单的C语言IoT模型示例，展示了如何从传感器读取数据并通过MQTT协议发送到云平台。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <MQTTClient.h>

#define ADDRESS     "tcp://broker.hivemq.com:1883"
#define CLIENTID    "ExampleClient"
#define TOPIC       "test/iot"
#define PAYLOAD     "Hello World!"
#define QOS         1
#define TIMEOUT     10000L

int main(int argc, char* argv[])
{
    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    int rc;
    MQTTClient_message pubmsg = MQTTClient_message_initializer;
    MQTTClient_deliveryToken token;

    // 创建MQTT客户端
    MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);

    // 设置连接选项
    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;

    // 连接到MQTT服务器
    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to connect, return code %d\n", rc);
        exit(EXIT_FAILURE);
    }

    // 设置消息内容
    pubmsg.payload = PAYLOAD;
    pubmsg.payloadlen = strlen(PAYLOAD);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;

    // 发布消息到指定主题
    MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token);
    printf("Waiting for publication on topic %s for client with ClientID: %s\n", TOPIC, CLIENTID);
    rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);
    printf("Message with delivery token %d delivered\n", token);

    // 断开连接并清理
    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);
    return rc;
}

这个示例展示了如何使用MQTT协议将数据发送到MQTT代理服务器。代码中使用了Eclipse Paho MQTT客户端库来简化MQTT通信的实现。