ESP32 MQTT – Publish DS18B20 Temperature Readings

 ESP32 MQTT – Publish DS18B20 Temperature Readings 

WOKWI程式

#include <WiFi.h>

#include "Adafruit_MQTT.h"

#include "Adafruit_MQTT_Client.h"

#include <OneWire.h>

#include <DallasTemperature.h>

#define WLAN_SSID "Wokwi-GUEST"

#define WLAN_PASS ""

/************************* Adafruit.io Setup ***************************/

#define AIO_SERVER      "broker.hivemq.com"

#define AIO_SERVERPORT  1883                   // use 8883 for SSL

#define AIO_USERNAME    ""

#define AIO_KEY         ""

#define AIO_FEED_1      "alex9ufo/esp32/ds18b20/temperature"

// Raspberry Pi Mosquitto MQTT Broker

//#define MQTT_HOST IPAddress(192, 168, 1, XXX)

// For a cloud MQTT broker, type the domain name

// Create an ESP8266 WiFiClient class to connect to the MQTT server.

WiFiClient client;

// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details.

Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_USERNAME, AIO_KEY);

/****************************** Feeds ***************************************/

// Setup feeds 'temp' and 'hmdt' for publishing.

Adafruit_MQTT_Publish tempPub = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME AIO_FEED_1);

// Setup a feed called 'onoff' for subscribing to changes to the ON/OFF button

// GPIO where the DS18B20 is connected to

const int oneWireBus = 4;          

// 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;

unsigned long lastMsg = 0;

// Function to connect and reconnect as necessary to the MQTT server.

// Should be called in the loop function and it will take care if connecting.

void MQTT_connect() {

  int8_t ret;

  // Stop if already connected.

  if (mqtt.connected()) {

    return;

  }

  Serial.print("Connecting to MQTT... ");

  uint8_t retries = 3;

  while ((ret = mqtt.connect()) != 0) { // connect will return 0 for connected

    Serial.println(mqtt.connectErrorString(ret));

    Serial.println("Retrying MQTT connection in 10 seconds...");

    mqtt.disconnect();

    delay(10000);  // wait 10 seconds

    retries--;

    if (retries == 0) {

      // basically die and wait for WDT to reset me

      while (1);

    }

  }

  Serial.println("MQTT Connected!");

}

void setup() {

  // Start the DS18B20 sensor

  sensors.begin();

 

  Serial.begin(115200);

  Serial.println();

  Serial.println();

  // Connect to WiFi access point.

  Serial.print("Connecting to ");

  Serial.println(WLAN_SSID);

  WiFi.begin(WLAN_SSID, WLAN_PASS);

  while (WiFi.status() != WL_CONNECTED) {

    delay(500);

    Serial.print(".");

  }

  Serial.println(); Serial.println("WiFi connected");

  Serial.println("IP address: "); Serial.println(WiFi.localIP());

}

void loop() {

  // Ensure the connection to the MQTT server is alive (this will make the first

  // connection and automatically reconnect when disconnected).  See the MQTT_connect

  // function definition further below.

  MQTT_connect();

  // this is our 'wait for incoming subscription packets and callback em' busy subloop

  // try to spend your time here:

  mqtt.processPackets(10000);

 

  // ping the server to keep the mqtt connection alive

  // NOT required if you are publishing once every KEEPALIVE seconds

 

  if(! mqtt.ping()) {

    mqtt.disconnect();

  }

 

  // Publish feeds

  unsigned long now = millis();

  if (now - lastMsg > 10000) {

    lastMsg = now;

    // New temperature readings

    sensors.requestTemperatures();

    // Temperature in Celsius degrees

    temp = sensors.getTempCByIndex(0);

    // Temperature in Fahrenheit degrees

    //temp = sensors.getTempFByIndex(0);

    Serial.println("Temperature: " +String(temp) + "°C");

    Serial.println("---");

    char strTemperature[20];

    sprintf(strTemperature, "%.1f", temp);

    tempPub.publish(strTemperature);

  }

}

Node-Red程式

[ { "id": "9a55977d9dd88494", "type": "mqtt in", "z": "72c4df790a4c757f", "name": "", "topic": "alex9ufo/esp32/ds18b20/temperature", "qos": "2", "datatype": "auto-detect", "broker": "2380dcc0d36d2c6a", "nl": false, "rap": true, "rh": 0, "inputs": 0, "x": 610, "y": 240, "wires": [ [ "ea3b6b36bf2cac5b" ] ] }, { "id": "ea3b6b36bf2cac5b", "type": "ui_gauge", "z": "72c4df790a4c757f", "name": "", "group": "4f4d1221d5fcd2d2", "order": 0, "width": 0, "height": 0, "gtype": "gage", "title": "gauge", "label": "°C", "format": "{{value}}", "min": "-55", "max": "125", "colors": [ "#00b500", "#e6e600", "#ca3838" ], "seg1": "25", "seg2": "50", "className": "", "x": 870, "y": 240, "wires": [] }, { "id": "2380dcc0d36d2c6a", "type": "mqtt-broker", "name": "", "broker": "broker.hivemq.com", "port": "1883", "clientid": "", "autoConnect": true, "usetls": false, "protocolVersion": "4", "keepalive": "60", "cleansession": true, "birthTopic": "", "birthQos": "0", "birthPayload": "", "birthMsg": {}, "closeTopic": "", "closeQos": "0", "closePayload": "", "closeMsg": {}, "willTopic": "", "willQos": "0", "willPayload": "", "willMsg": {}, "userProps": "", "sessionExpiry": "" }, { "id": "4f4d1221d5fcd2d2", "type": "ui_group", "name": "溫度", "tab": "096dc3f20d4aa28b", "order": 1, "disp": true, "width": "6", "collapse": false, "className": "" }, { "id": "096dc3f20d4aa28b", "type": "ui_tab", "name": "MQTT DS18B20", "icon": "dashboard", "order": 128, "disabled": false, "hidden": false } ]