编写arduino uno采取mqtt协议连接云平台的代码

以下是一个基本的Arduino Uno使用MQTT协议连接到云平台的代码示例：

#include <WiFi.h>
#include <PubSubClient.h>

// WiFi网络凭证
const char* ssid = "your-ssid";
const char* password = "your-password";

// MQTT服务器IP和端口号
const char* mqtt_server = "your-mqtt-server-ip";
int mqtt_port = 1883;

// MQTT客户端实例化
WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
Serial.begin(9600);
// 连接到WiFi网络
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to WiFi...");
}
Serial.println("Connected to WiFi network");

// 连接MQTT服务器
client.setServer(mqtt_server, mqtt_port);
while (!client.connected()) {
Serial.println("Connecting to MQTT server ...");
if (client.connect("your-client-id")) {
Serial.println("Connected to MQTT server");
} else {
Serial.print("Failed to connect to MQTT server, rc=");
Serial.print(client.state());
Serial.println(" retrying in 5 seconds");
delay(5000);
}
}

// 订阅MQTT主题
client.subscribe("your-subscribe-topic");
}

void loop() {
// 在此添加任何需要执行的代码

// 检测MQTT连接，如果订阅主题有消息，则进行处理
if (!client.connected()) {
reconnect();
}
client.loop();
}

// 重新连接函数
void reconnect() {
// 循环尝试连接MQTT服务器，直到成功为止
while (!client.connected()) {
Serial.println("Attempting MQTT connection...");
// 尝试连接MQTT服务器
if (client.connect("your-client-id")) {
Serial.println("Connected to MQTT server");
// 订阅MQTT主题
client.subscribe("your-subscribe-topic");
} else {
Serial.print("Failed to connect to MQTT server, rc=");
Serial.print(client.state());
Serial.println(" retrying in 5 seconds");
delay(5000);
}
}
}

// 处理接收到的MQTT消息
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message received [");
Serial.print(topic);
Serial.print("]: ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
}

注意: 代码示例中的 “your-ssid”, “your-password”, “your-mqtt-server-ip”, “your-client-id” 和 “your-subscribe-topic” 都需要根据实际情况填写和替换。 示例如下：

const char* ssid = "MyWiFi";
const char* password = "MyWiFiPassword";
const char* mqtt_server = "192.168.0.10";
client.connect("Arduino1");
client.subscribe("sensor/temperature");