// Arduino Uno with a 'main' function.
// There is no Arduino layer.
//
// The generated assembly can be viewed:
//   Right click on source code.
//   Select "Command Palette F1"
//   Type "asse" to search for:
//     "View Compiled Assembly Code Listing"
//   Select that and wait for the project to be compiled.
//   If that is successful, then a new tab appears.
//   It is a file "sketch.lst" 
//   That is the generated assembly code.
//   It also works with Arduino code.
//   With Arduino code is is allowed to use
//   direct register access or make a block
//   of assembly code.

#include <avr/io.h>
#include <util/delay.h>

int main(void) 
{
  DDRB = (1 << PORTB5);

  while(1)
  {
    for (int i = 0; i < 200; i++) 
    {
      PORTB |= (1 << PORTB5);
      _delay_us(1000UL);
      PORTB &= ~(1 << PORTB5);
      _delay_us(1000UL);
    }
    _delay_us(500000UL);
  }
}