Tic-Tac USBtinyISP Programmer

Tic-Tac-USBtinyISP-Programmer 4_3

What's with mint boxes and electronics? Beats me, but they are somehow made for each other. I had built ladyada's USBtinyISP v1.0 circuit(used to program Atmel microcontrollers) on a breadboard which I used every other day. It worked sporadically(and never at hour of need), used up half of my breadboard and looked ugly. So I decided to try my hand at home PCB fabrication and build it in, of course, a tiny tic-tac box.

Tic-Tac-USBtinyISP-Programmer Fab_PCB 4_3

The schematics provided by ladyada are not only double sided but also uses vias which are extremely difficult to make using home-fabrication techniques. Since it was my first attempt at making a PCB, I redesigned the circuit as simple single-sided board in Eagle. There is provision for using either crystal or ceramic resonator. A USB-B jack is provided for connectivity to computer.

Tic-Tac-USBtinyISP-Programmer Single 4_3

The ICSP pins were extended using ribbon cable to another tiny tic-tac box with a similarly tiny PCB for ICSP connector. The brains is an ATtiny2313 miccrocontroller which requires another programmer to program. To get out of this chicken-and-egg problem, I used a Ghetto Programmer but it can be accomplished with a working Arduino or by purchasing a pre-programmed ATtiny2313.