#include <TimerOne.h>  // Ensure this library is correctly installed

const int LED_PIN = 13;  // Built-in LED on most Arduino boards
volatile unsigned long millisCount = 0;
bool ledState = LOW;

void setup() {
  pinMode(LED_PIN, OUTPUT);  // Initialize LED pin as output
  Timer1.initialize(1000);   // Initialize Timer1 to trigger every 1000 microseconds (1 ms)
  Timer1.attachInterrupt(timerISR);  // Attach our ISR to the timer
}

void loop() {
  // Empty loop as the code is interrupt-driven
}

void timerISR() {
  millisCount++;
  if (millisCount >= 1000) {  // Every 1000 ms (1 second)
    millisCount = 0;
    ledState = !ledState;    // Toggle the LED state
    digitalWrite(LED_PIN, ledState);  // Write the LED state to the pin
  }
}