I am a firm believer in “standing on the shoulders of giants” and borrowing ideas that already exist and combining, building on them or delivering your own take on them – after all why re-invent the wheel, just because you happen to want to use a wheel in your design? This was good enough for Sir Isaac Newton and Linus Torvalds, so why not ordinary people like me?
The best example I have found is that by Asher Glick:
This was also used as the foundation for the one built by Hari Wiguna:
I have decided that I will use a bare ATmega328P, as I can buy these from RS for £2.14 each, I can probably do away with the requirement for an external crystal or resonator by running at 8MHz from the internal clock, so the only other costs will be a suitable perfboard and some LEDs.
I am using some perfboard I bought from Ebay – 10 pieces of 7x9cm at £1.80, or £0.18 each.
The LEDs came from an Ebay auction for 100 x 5mm RGB LEDs that I won for £5.65 (inc P&P) which makes for £0.0565 each or £3.616 for the 64 required for this project.
This makes the total cost of this project, excluding any additional wire or solder, to be just under £6.00.
I have drawn up the schematic in Eagle:
Legs bent out at 90 degrees:
Legs bent back around ready for soldering: