Build a Wi-Fi Weather Station with ESP32

#include <WiFi.h>
#include <WebServer.h>
#include <Wire.h>
#include <DHT.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Example for a classic ESP32 development board.
// Confirm the pinout and OLED address for your hardware.
const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";
DHT dht(4, DHT22);
Adafruit_SSD1306 display(128, 64, &Wire, -1);
WebServer server(80);
float temperature = NAN, humidity = NAN;
unsigned long lastRead = 0;
bool oledReady = false;

void setup() {
  Serial.begin(115200);
  dht.begin();
  Wire.begin(21, 22);
  oledReady = display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  if (!oledReady) Serial.println("OLED not found; check wiring/address.");
  WiFi.begin(ssid, password);
  unsigned long started = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - started < 20000) {
    delay(250);
  }
  if (WiFi.status() == WL_CONNECTED) Serial.println(WiFi.localIP());
  else Serial.println("Wi-Fi not connected. Sensor readings still available.");
  server.on("/", []() {
    if (isnan(temperature) || isnan(humidity)) {
      server.send(503, "text/plain", "Waiting for a valid sensor reading.");
      return;
    }
    String body = "<!doctype html><meta name='viewport' content='width=device-width'>";
    body += "<meta http-equiv='refresh' content='5'><title>ElectroShelf Weather</title>";
    body += "<h1>My ESP32 Weather Station</h1><p>Temperature: ";
    body += String(temperature, 1) + " C</p><p>Humidity: ";
    body += String(humidity, 1) + " %</p>";
    server.send(200, "text/html", body);
  });
  server.begin();
}

void loop() {
  server.handleClient();
  if (millis() - lastRead < 2500) return;
  lastRead = millis();
  temperature = dht.readTemperature();
  humidity = dht.readHumidity();
  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("Sensor read failed; check wiring and pull-up resistor.");
    return;
  }
  Serial.printf("Temperature: %.1f C, Humidity: %.1f %%\n", temperature, humidity);
  if (!oledReady) return;
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("ElectroShelf Weather");
  display.printf("Temp: %.1f C\n", temperature);
  display.printf("Humidity: %.1f %%\n", humidity);
  display.println(WiFi.status() == WL_CONNECTED ? WiFi.localIP().toString() : "Wi-Fi offline");
  display.display();
}