If you look at the diagram, you can immidiatly see
that this display isn't multiplexed because the Common Cathode is
connected to ground. I made an upcounter, by using the EEPROM of the AVR,
this makes the program pretty short. I also did put a so called 'lamp
test' piece of code in the routine, easy for testing different kind of
Common Cathode LED displays. Simply put the segments data into an EEPROM
table, this saves a lot of program lines.