The AAduino is an Arduino compatible microcontroller board, created by Swedish embedded systems engineer Johan Kanflo, that’s the size of a AA battery. The AAduino is designed to fit comfortably inside of one of the bays of a standard 3xAA battery holder. The resulting ‘Duino in a very small, reasonably powerful, wireless node will endless application possibilities. Johan describes the impetus for the design.
I have been using Nathan Chantrell’s Tiny328 for quite some time as my Swiss Army knife ISM radio node. Now I wanted a more slim ISM node as my setup with a Tiny328 on a breadboard is not very “deployable”. I could of course 3D print a case for the Tiny328 but I have limited access to 3D printers and do not feel I have the time to explore that exciting part of the maker world just yet. This leaves me with finding off the shelf project boxes with a compartment for 2x AA batteries and the “radioduino” (and in an acceptable form factor). That search came up disappointingly, and surprisingly, short. I did have a set of standard eBay AA battery holders and looking at the 3x variant it occurred to me. I needed to shrink the radio node, and the AAduino was born.
The AAduino is software-compatible with Arduino and powered by an ATMega328p microcontroller and fitted with an RFM69C radio transceiver, two DS18B20 temperature sensors, and an indicator LED. Johan used Keystone battery spring clips attached to the PCB to allow it to fit inside of a bay of the holder and to make electrical contact with the battery power source. The RFM69C board was somewhat wider than a AA battery, so he had to shave down the edges on the PCB to get it to fit.
The AAduino is not the smallest ‘Duino form factor out there. There are numerous other, smaller versions, but the bright idea here was to design it around a standard battery holder, giving you a fully-functional, wireless Arduino, with power, inside of its own ready-made project box. Sweet.