const int ledPin = 21; // Onboard LED pin (usually GPIO 2 for ESP32)

void setup() {
  pinMode(ledPin, OUTPUT); // Set the LED pin as an output
}

void loop() {
  digitalWrite(ledPin, 1); // Turn the LED on
  delay(1000);                // Wait for 1 second
  digitalWrite(ledPin, 0);  // Turn the LED off
  delay(1000);                // Wait for 1 second
}