// This is only for ATmega microcontrollers.
// They have a pin toggle command that uses a single clock cycle.
//
// In Wokwi:
//   Right click this text for Command Pallette or press F1.
//   then search for 'assembly' en click to View the generate assembly code.
//   A new tab was created with "sketch.lst" with the assembly code.

void setup() 
{
  pinMode(3, OUTPUT);
}

void loop() 
{
  PIND = bit(PD3);                   // or (1 << PD3);
  __builtin_avr_delay_cycles(99);
  PIND = bit(PD3);
  __builtin_avr_delay_cycles(999);
  PIND = bit(PD3);
}