Just a simple board that has two ATTiny processors powered by a micro USB connector. The rest is up to you!
This project was basically an experiment in order to try out a new (to me) schematic capture and PCB designer tool called DipTrace. Overall, I liked Diptrace to make a tiny PCB like this. However, I would not consider this to be anywhere near equivalent to professional packages like Altium.
I also used this project as an excuse to purchase a solder paste stencil from OSH Stencils and to play with my new hot air rework station from Sparkfun. This board IS hand solder-able! In fact the first of the boards that I assembled, I did by hand. The only tricky component was the USB connector. I was able to do this fairly easy using the drag-soldering technique.
Micro USB power input to two ATTiny MCU's. There are two different ATTinys on this board. An ATTiny84 and an ATTiny85. These MCUs are great because they can be used with no additional components. In fact, on this board, the only additional components are some filter capacitors for the power rail and a header for the programmer interface.
Other than that, the board is just a widget that can be used to add a little bit of logic to anything. I have exposed an array of copper pads for every pin. This makes it easy to add LEDs or to wire to just about any sensor.
In total, this costs less than $7 per board for the components plus about $2.80 for the PCB itself.
Order your own
Order the PCB here:
Order your parts here:
http://www.digikey.com/short/3bw5cn (enough parts for three board with several spares of each part (in case you screw up soldering)