- Size: 35 x 26 x 8mm

- ATtiny85 Microcontroller with Micronucleus USB-bootloader.

- CR2032 coin cell holder on the back (can run for weeks or even months when using the micro's sleep functions)

- Transistor (NPN in current sink configuration) for switching larger currents

- All peripherals wired so the impact is minimal if you want to connect other devices

- Micro USB connector for power and uploading firmware

- All micro pins and GND and VCC broken out on SMT pads

- 4 mounting holes (3mm) for easy mounting

User input

- Tact switch

- SPST slide switch

- Potentiometer (100K)

User output

- Piezo buzzer

- Bright LED

To be honest, I can't get the bootloader to work properly (it freezes the USB-hub of my MacBook Pro sometimes) and this is a little above my head as well. I'm not sure if this is a software or hardware issue.

I can imagine this being a really nice sub-$10 starter-board for a lot of people (you could essentially use them as throwies!) but that would require perfect operation and meticulous documentation, application examples etc.

Right now, I don't have time to develop this project further; if someone wants to pick this up, or create something similar, feel free to do so.