Some years ago a have started building Clone PI AVR. Made a PCB, soldered all the components and … and never found time to finish it until today. Well I haven’t finished it yet but at lest gave it a first test run. For the screen and buttons i have re-purposed some front panel of some old router. Now i see that i will have to put it in to another box for better mounting on the metal detector itself but this time it was good enough for test run. For Atmega programming I used Mini Pro TL866 programmer I have bought while ago – works like a charm. You can see some photos and video on work in progress.
Circuit of Clopne PI AVR: