// A test for the Discord channel.
// Original: https://wokwi.com/projects/432367544589072385
// Removed everything except the timer with interrupt.
//
// Timer1 runs, interrupts works, all well.
// It is a 1Hz timer, usually a 1kHz (1000Hz)'tick' is used
// in a embedded system.

volatile unsigned int counter;

void setup() 
{
  Serial.begin(115200);
  Serial.println("Test timer with interrupt");

  setupTimer1();
}

void setupTimer1() 
{
  cli();
  TCCR1A = 0;
  TCCR1B = 0;

  OCR1A = 15624;               // Compare match register (1 Hz)
  TCCR1B |= (1 << WGM12);      // CTC mode
  TCCR1B |= (1 << CS12) | (1 << CS10); // Prescaler 1024
  TIMSK1 |= (1 << OCIE1A);     // Enable Timer1 compare interrupt
  sei();
}

void loop() 
{
  // This is not 100% safe, since an interrupt might
  // happen between retrieving the two bytes 
  // of the variable.
  Serial.print(counter);
  Serial.print(", ");
  delay(100);
}

//ISR
ISR(TIMER1_COMPA_vect) 
{
  counter++;
}