探索ESP8285（3）通过EMQX服务器点亮一个LED灯

article/2025/9/27 10:04:28

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在上一个博客的基础上探索ESP8285（2）搭建Windows版MQTT服务器

我们来通过EMQX服务器点亮ESP8285模块上的LED灯。

首先查得ESP8285模块上的LED灯引脚是GPIO4，低电平亮起，所以我们先定义GPIO口

在setup里设置引脚为输出模式

在连接里修改订阅的主题为 /mqtt/test/

在callback函数里修改LED引脚参数

编译上传到ESP8285模块上，接下来测试效果：

打开MQTTBox，连接好服务器，在Payload上输入1，然后按Publish发布信息。

ESP8285模块接收到信息后会自动打开LED。如果是发送0或者其他的字符，LED灯关闭。

以下是整个测试代码：

    #include <ESP8266WiFi.h>#include <PubSubClient.h>#define PIN_LED 4// Update these with values suitable for your network.const char* ssid = "....";const char* password = "....";//const char* mqtt_server = "iot.eclipse.org";const char* mqtt_server = "192.168.1.162";const String macAddress = WiFi.macAddress();//const char* clientID = macAddress.c_str();const char* clientID = "client001";const char* userName = "user001";const char* passWord = "psd001";WiFiClient espClient;PubSubClient client(espClient);long lastMsg = 0;char msg[50];int value = 0;void setup() {      pinMode(PIN_LED, OUTPUT);     // Initialize the LED pin as an outputSerial.begin(115200);setup_wifi();client.setServer(mqtt_server, 1883);client.setCallback(callback);}void setup_wifi() {delay(10);// We start by connecting to a WiFi networkSerial.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 arrived [");Serial.print(topic);Serial.print("] ");for (int i = 0; i < length; i++) {Serial.print((char)payload[i]);}Serial.println();// Switch on the LED if an 1 was received as first characterif ((char)payload[0] == '1') {digitalWrite(PIN_LED, LOW);   // Turn the LED on (Note that LOW is the voltage level// but actually the LED is on; this is because// it is acive low on the ESP-01)} else {digitalWrite(PIN_LED, HIGH);  // Turn the LED off by making the voltage HIGH}}void reconnect() {// Loop until we're reconnectedwhile (!client.connected()) {Serial.print("Attempting MQTT connection...");// Attempt to connectif (client.connect(clientID,userName,passWord)) {Serial.println("connected");// Once connected, publish an announcement...client.publish("/mqtt/test/", "hello world");// ... and resubscribeclient.subscribe("/mqtt/test/#");} else {Serial.print("failed, rc=");Serial.print(client.state());Serial.println(" try again in 5 seconds");// Wait 5 seconds before retryingdelay(5000);}}}void loop() {if (!client.connected()) {reconnect();}client.loop();//      long now = millis();
//      if (now - lastMsg > 2000) {
//        lastMsg = now;
//        ++value;
//        snprintf (msg, 75, "hello world #%ld", value);
//        Serial.print("Publish message: ");
//        Serial.println(msg);
//        client.publish("outTopic", msg);
//      }}