For some Arduino projects, you don’t actually need that many IO pins. That’s exactly the case when I tried to build a simple RGB throwie that would cycle through colours. I was looking for a cheaper alternative to the Arduino UNO’s ATmega328P when I stumbled across this post by MIT’s High-Low Tech lab.
They developed a library for programming the 8-pins ATtiny45/85 from the Arduino IDE. It’s a very smart solution to use permanently in some low pin-usage projects, but you still need to hook up individual wires from your programmer to the ATtiny to be able to program it. That’s when I came up with the idea of the BareDuino Micro.
The BareDuino Micro solves this problem. It’s got an ATtiny45 or 85, on-board ISP header for easy reprogramming, a power LED and battery connections. The pins are all broken out in the same way as the DIP packaged ATtiny, so you can easily plug it into a breadboard. I originally designed the board for a personal project, but the design files are available at the GitHub repository.
For more detail: BareDuino Micro