referent from : http://www.rjhcoding.com/avr-asm-delay-subroutine.php clock cycle calculation table : https://docs.google.com/spreadsheets/d/1Gf-PrrAeJ54bnab67ngiJQ6b6_vJOCGqP-2Q-5yNoVo/edit?gid=0#gid=0