mqtt协议怎么用esp8266
时间: 2024-05-12 18:11:50 浏览: 18
MQTT(Message Queuing Telemetry Transport)是一种轻量级的消息传输协议,通常用于物联网(IoT)设备之间的通信。ESP8266是一款便捷的Wi-Fi模块,支持多种开源固件,如NodeMCU等,可以与MQTT协议配合使用。
使用ESP8266连接MQTT服务器需要进行以下几个步骤:
1. 安装MQTT库:在Arduino IDE中选择“工具”-“管理库”,搜索并安装PubSubClient库。
2. 编写连接代码:在Arduino IDE中打开新的窗口,输入以下代码:
```
#include <WiFiClient.h>
#include <PubSubClient.h>
// Replace with your network credentials
const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
// Replace with your MQTT broker IP address
const char* mqtt_server = "your_MQTT_broker_IP_address";
WiFiClient espClient;
PubSubClient client(espClient);
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
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();
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("outTopic", "hello world");
// ... and resubscribe
client.subscribe("inTopic");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
}
```
3. 更改网络和MQTT服务器的连接信息:替换代码中的Wi-Fi网络名称和密码,以及MQTT服务器的IP地址。
4. 编译和上传代码:将代码上传到ESP8266模块,并在串口监视器中查看连接状态和消息传输情况。
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