This is a simple hand held iButton reader for collecting results after a small event, to dispense with the need for a PC on-site.
It displays the competitors run-time, and control order with split times so the results can be copied to a paper list. The ibuttons can be read again later with a PC, at home, for web publishing etc.
Features are somewhat limited by the 2k byte limit of the 16F628 and the free-to-use PIC Mikro-basic compiler, but it still works great.
If you move to a 16F648 , which has 4k available for the program, then you will have to pay for the full compiler !
Schematic below :-
Reader software can be downloaded here.