IoT Lab - Connect ESP32 with Homebridge

Schematic – ESP32 with Humidity and Temperature Sensor and LED Lights

If you haven't setup the ESP32 microcontroller and Homebridge you should setup that first!

Code

#include "DHT.h"
#include <HTTPClient.h>
#include <WiFi.h>
#include <WebServer.h>
 
#define DHTPIN 25     // what pin we're connected to
#define DHTTYPE DHT22   // DHT 22  (AM2302)
#define LED 12 // LED pin

DHT dht(DHTPIN, DHTTYPE);

// Replace with your network credentials
const char* ssid     = "WiFi-name";
const char* password = "password";

WebServer server(80);

void setup() {
  Serial.begin(115200); 

  // Start humidity sensor
  dht.begin();

  pinMode(LED, OUTPUT); // Set the LED pin as an OUTPUT 

  // Connect to Wi-Fi network
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  // Start the server
  server.on("/", handleRoot);
  server.on("/on", ledOn);
  server.on("/off", ledOff);
  server.begin();
  Serial.println("Server started");
}

void loop() {
  // Open connection
  server.handleClient();

  // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius
  float t = dht.readTemperature();
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  
  Serial.print("Humidity: "); 
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: "); 
  Serial.print(t);
  Serial.println(" *C ");

  // Send the current temperature to Homebridge for updating value
  if(WiFi.status() == WL_CONNECTED){
      HTTPClient http;

      // http://192.168.137.253:51828/?accessoryId=sn1&value=23

      String serverName = "http://192.168.137.253:51828/"; // Your homebridge IP
      String accessoryId = "sn1"; // Your accessory id
      String serverPath = serverName + "?accessoryId=" + accessoryId + "&value=" + t;
      
      // Your Domain name with URL path or IP address with path
      http.begin(serverPath.c_str());
      
      // If you need Node-RED/server authentication, insert user and password below
      //http.setAuthorization("REPLACE_WITH_SERVER_USERNAME", "REPLACE_WITH_SERVER_PASSWORD");
      
      // Send HTTP GET request (Send the current temperature to Homebridge)
      int httpResponseCode = http.GET();
      
      if (httpResponseCode>0) {
        Serial.print("HTTP Response code: ");
        Serial.println(httpResponseCode);
        String payload = http.getString();
        Serial.println(payload);
      }
      else {
        Serial.print("Error code: ");
        Serial.println(httpResponseCode);
      }
      // Free resources
      http.end();
    }
    else {
      Serial.println("WiFi Disconnected");
    }
}

void handleRoot() {
  // return message for testing
  server.send(200, "text/plain", "Hello from ESP32!");
}

void ledOn() {
  digitalWrite(LED,HIGH);
  greenLedStatus = true;
  // return light status to Homebridge
  server.send(200, "text/plain", "The light is on!");
}

void ledOff() {
  digitalWrite(LED,LOW);
  greenLedStatus = false;
  // return light status to Homebridge
  server.send(200, "text/plain", "The light is off");
}