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mqtt_esp8266wemos - simple mqtt sender and receiver for wemos d1 mini. mac address is part of topic.
/*
Simple wemos D1 mini MQTT example
This sketch demonstrates the capabilities of the pubsub library in combination
with the ESP8266 board/library.
It connects to the provided access point using dhcp, using ssid and pswd
It connects to an MQTT server ( using mqtt_server ) then:
- publishes "connected"+uniqueID to the [root topic] ( using topic )
- subscribes to the topic "[root topic]/composeClientID()/in" with a callback to handle
- If the first character of the topic "[root topic]/composeClientID()/in" is an 1,
switch ON the ESP Led, else switch it off
- after a delay of "[root topic]/composeClientID()/in" minimum, it will publish
a composed payload to
It will reconnect to the server if the connection is lost using a blocking
reconnect function.
*/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
const char* ssid = "whub4";
const char* pswd = "simple8713";
const char* mqtt_server = "192.168.1.91";
const char* topic = "wemos"; // rhis is the [root topic]
long timeBetweenMessages = 1000 * 20 * 1;
WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
int value = 0;
int status = WL_IDLE_STATUS; // the starting Wifi radio's status
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, pswd);
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 character
if ((char)payload[0] == '1') {
digitalWrite(BUILTIN_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(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
}
}
String macToStr(const uint8_t* mac)
{
String result;
for (int i = 0; i < 6; ++i) {
result += String(mac[i], 16);
if (i < 5)
result += ':';
}
return result;
}
String composeClientID() {
uint8_t mac[6];
WiFi.macAddress(mac);
String clientId;
clientId += "esp-";
clientId += macToStr(mac);
return clientId;
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
String clientId = composeClientID() ;
clientId += "-";
clientId += String(micros() & 0xff, 16); // to randomise. sort of
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish(topic, ("connected " + composeClientID()).c_str() , true );
// ... and resubscribe
// topic + clientID + in
String subscription;
subscription += topic;
subscription += "/";
subscription += composeClientID() ;
subscription += "/in";
client.subscribe(subscription.c_str() );
Serial.print("subscribed to : ");
Serial.println(subscription);
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.print(" wifi=");
Serial.print(WiFi.status());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
// confirm still connected to mqtt server
if (!client.connected()) {
reconnect();
}
client.loop();
long now = millis();
if (now - lastMsg > timeBetweenMessages ) {
lastMsg = now;
++value;
String payload = "{\"micros\":";
payload += micros();
payload += ",\"counter\":";
payload += value;
payload += ",\"client\":";
payload += composeClientID();
payload += "}";
String pubTopic;
pubTopic += topic ;
pubTopic += "/";
pubTopic += composeClientID();
pubTopic += "/out";
Serial.print("Publish topic: ");
Serial.println(pubTopic);
Serial.print("Publish message: ");
Serial.println(payload);
client.publish( (char*) pubTopic.c_str() , (char*) payload.c_str(), true );
}
}
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