Connect ESP3266 to MQTT
Connect the board that is already connected with the sensors to your computer.
Open Arduino on your computer and paste the following codes to Arduino's workspace.
/*
Rui Santos
Complete project details at https://RandomNerdTutorials.com/esp8266-nodemcu-mqtt-publish-ds18b20-arduino/
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files.
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
*/
//\\
//\\ Modified by Sovatha Pann, Embedded Systems Engineering, Burapha University
//\\
#include <OneWire.h>
#include <DallasTemperature.h>
#include <ESP8266WiFi.h>
#include <Ticker.h>
#include <AsyncMqttClient.h>
#define WIFI_SSID "Sovatha's S10" //wifi's name
#define WIFI_PASSWORD "" // wifi's password
// Raspberri Pi Mosquitto MQTT Broker
#define MQTT_HOST IPAddress(192, 168, 43, 145) // raspberry pi's ip address
// For a cloud MQTT broker, type the domain name
//#define MQTT_HOST "example.com"
#define MQTT_PORT 1883 // mqtt's port (1883 is prefered but you still customize)
// Temperature MQTT Topics
#define MQTT_PUB_TEMP "sensors"
// GPIO where the DS18B20 is connected to
const int oneWireBus = 2;
// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(oneWireBus);
// Pass our oneWire reference to Dallas Temperature sensor
DallasTemperature sensors(&oneWire);
// Temperature value
float temp;
AsyncMqttClient mqttClient;
Ticker mqttReconnectTimer;
WiFiEventHandler wifiConnectHandler;
WiFiEventHandler wifiDisconnectHandler;
Ticker wifiReconnectTimer;
unsigned long previousMillis = 0; // Stores last time temperature was published
const long interval = 10000; // Interval at which to publish sensor readings
void connectToWifi() {
Serial.println("Connecting to Wi-Fi...");
WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
}
void onWifiConnect(const WiFiEventStationModeGotIP& event) {
Serial.println("Connected to Wi-Fi.");
connectToMqtt();
}
void onWifiDisconnect(const WiFiEventStationModeDisconnected& event) {
Serial.println("Disconnected from Wi-Fi.");
mqttReconnectTimer.detach(); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
wifiReconnectTimer.once(2, connectToWifi);
}
void connectToMqtt() {
Serial.println("Connecting to MQTT...");
mqttClient.connect();
}
void onMqttConnect(bool sessionPresent) {
Serial.println("Connected to MQTT.");
Serial.print("Session present: ");
Serial.println(sessionPresent);
}
void onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {
Serial.println("Disconnected from MQTT.");
if (WiFi.isConnected()) {
mqttReconnectTimer.once(2, connectToMqtt);
}
}
/*void onMqttSubscribe(uint16_t packetId, uint8_t qos) {
Serial.println("Subscribe acknowledged.");
Serial.print(" packetId: ");
Serial.println(packetId);
Serial.print(" qos: ");
Serial.println(qos);
}
void onMqttUnsubscribe(uint16_t packetId) {
Serial.println("Unsubscribe acknowledged.");
Serial.print(" packetId: ");
Serial.println(packetId);
}*/
void onMqttPublish(uint16_t packetId) {
Serial.print("Publish acknowledged.");
Serial.print(" packetId: ");
Serial.println(packetId);
}
void setup() {
sensors.begin();
Serial.begin(115200); // baudrate
Serial.println();
wifiConnectHandler = WiFi.onStationModeGotIP(onWifiConnect);
wifiDisconnectHandler = WiFi.onStationModeDisconnected(onWifiDisconnect);
mqttClient.onConnect(onMqttConnect);
mqttClient.onDisconnect(onMqttDisconnect);
//mqttClient.onSubscribe(onMqttSubscribe);
//mqttClient.onUnsubscribe(onMqttUnsubscribe);
mqttClient.onPublish(onMqttPublish);
mqttClient.setServer(MQTT_HOST, MQTT_PORT);
// If your broker requires authentication (username and password), set them below
//mqttClient.setCredentials("REPlACE_WITH_YOUR_USER", "REPLACE_WITH_YOUR_PASSWORD");
connectToWifi();
}
void loop() {
unsigned long currentMillis = millis();
// Every X number of seconds (interval = 10 seconds)
// it publishes a new MQTT message
if (currentMillis - previousMillis >= interval) {
// Save the last time a new reading was published
previousMillis = currentMillis;
// New temperature readings
sensors.requestTemperatures();
// Temperature in Celsius degrees
temp = sensors.getTempCByIndex(0);
// Temperature in Fahrenheit degrees
//temp = sensors.getTempFByIndex(0);
// Publish an MQTT message on topic esp/ds18b20/temperature
uint16_t packetIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, true, ("temp,site=room1 value=" + String(temp)).c_str()); // publish to mqtt broker
Serial.printf("Publishing on topic %s at QoS 1, packetId: %i ", MQTT_PUB_TEMP, packetIdPub1);
Serial.printf("Message: %.2f \n", temp);
}
}
Compile and upload.
Wait until finish and open a serial monitor which is on the top right of the program to see how things work.
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