33170273a9
Many users load the sketch having only changed WiFi SSID and password. When multiple users attempt to connect to the same broker using same client ID, they get rejected. Currently the chances of connecting to broker.mqtt-dashboard.com using "ESP8266Client" ID are fairly slim. This change adds a random number to the client ID, increasing chances of connection for new users of this library.
133 lines
3.6 KiB
C++
133 lines
3.6 KiB
C++
/*
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Basic ESP8266 MQTT example
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This sketch demonstrates the capabilities of the pubsub library in combination
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with the ESP8266 board/library.
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It connects to an MQTT server then:
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- publishes "hello world" to the topic "outTopic" every two seconds
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- subscribes to the topic "inTopic", printing out any messages
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it receives. NB - it assumes the received payloads are strings not binary
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- If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
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else switch it off
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It will reconnect to the server if the connection is lost using a blocking
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reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
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achieve the same result without blocking the main loop.
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To install the ESP8266 board, (using Arduino 1.6.4+):
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- Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
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http://arduino.esp8266.com/stable/package_esp8266com_index.json
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- Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
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- Select your ESP8266 in "Tools -> Board"
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*/
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#include <ESP8266WiFi.h>
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#include <PubSubClient.h>
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// Update these with values suitable for your network.
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const char* ssid = "........";
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const char* password = "........";
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const char* mqtt_server = "broker.mqtt-dashboard.com";
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WiFiClient espClient;
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PubSubClient client(espClient);
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long lastMsg = 0;
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char msg[50];
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int value = 0;
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void setup_wifi() {
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delay(10);
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// We start by connecting to a WiFi network
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Serial.println();
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Serial.print("Connecting to ");
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Serial.println(ssid);
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WiFi.begin(ssid, password);
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while (WiFi.status() != WL_CONNECTED) {
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delay(500);
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Serial.print(".");
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}
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randomSeed(micros());
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Serial.println("");
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Serial.println("WiFi connected");
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Serial.println("IP address: ");
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Serial.println(WiFi.localIP());
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}
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void callback(char* topic, byte* payload, unsigned int length) {
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Serial.print("Message arrived [");
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Serial.print(topic);
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Serial.print("] ");
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for (int i = 0; i < length; i++) {
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Serial.print((char)payload[i]);
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}
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Serial.println();
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// Switch on the LED if an 1 was received as first character
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if ((char)payload[0] == '1') {
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digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
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// but actually the LED is on; this is because
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// it is acive low on the ESP-01)
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} else {
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digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
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}
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}
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void reconnect() {
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// Loop until we're reconnected
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while (!client.connected()) {
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Serial.print("Attempting MQTT connection...");
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// Create a random client ID
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String clientId = "ESP8266Client-";
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clientId += String(random(0xffff), HEX);
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// Attempt to connect
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if (client.connect(clientId.c_str())) {
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Serial.println("connected");
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// Once connected, publish an announcement...
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client.publish("outTopic", "hello world");
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// ... and resubscribe
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client.subscribe("inTopic");
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} else {
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Serial.print("failed, rc=");
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Serial.print(client.state());
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Serial.println(" try again in 5 seconds");
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// Wait 5 seconds before retrying
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delay(5000);
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}
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}
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}
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void setup() {
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pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
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Serial.begin(115200);
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setup_wifi();
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client.setServer(mqtt_server, 1883);
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client.setCallback(callback);
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}
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void loop() {
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if (!client.connected()) {
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reconnect();
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}
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client.loop();
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long now = millis();
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if (now - lastMsg > 2000) {
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lastMsg = now;
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++value;
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snprintf (msg, 75, "hello world #%ld", value);
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Serial.print("Publish message: ");
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Serial.println(msg);
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client.publish("outTopic", msg);
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}
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}
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