I’ve been using Arduino boards in their various flavors for years, but lately I’ve started to gravitate more and more to the Nano for simple projects. Available for just a few dollars, I keep several of these boards in my parts cache, ready for use in my next idea. Having a Nano handy allowed me to add RGB lighting to my CNC light graffiti machine in just a few hours, and what I realized is that I’ve developed a sort of template that could be useful to others.
In this semi-standard Nano setup, I use a (two) CR2032 battery pack that provides both a nominal 6V power supply, and a switch to cut power off when needed. Best of all, this power supply nearly matches the Nano’s footprint, so I can either use zip-ties or shrink wrap tubing to form everything into a compact package — ready to throw into a project at a moment’s notice!
User interface to the Nano is provided by a four-position DIP switch wired to ground. This is set as an “INPUT_PULLUP” in the program, meaning there’s no worry about floating inputs or external resistors. The only downside to this design is that if you need to make changes (or swap out the batteries) you have to cut off the heat shrink. For quick embedded projects and prototypes, however, this basic template could be just the thing!