A Battery-Sized Arduino
The Arduino platform is one of the most versatile on the market, and its popularity has given rise to dozens of variants. In the vast majority of cases, what is sought is to guarantee compatibility, but there are designs out there that aim to reduce the size of the PCB as much as possible. That is how we arrive at the AAduino, a clone created by the Swedish Johan Kanflo. The hardware is based on the ATMega328p, and it is so small that it takes the place of a AA battery.
One of the most critical aspects that every DIY enthusiast must solve is power. Thanks to the magic of lithium, today it is possible to use batteries with solid performance and increasingly interesting dimensions, but there are times when the cost drastically outweighs the benefit, and the user must look for other options. Fortunately, hardware is relatively flexible, and even an improvised power source can be useful in home projects. As an example, an Arduino Uno recommends between 7 and 12 volts, and with some adjustments, it is reasonable to make the ATMega328p run at a lower frequency to reduce energy demand. How low can you go?
Swedish developer Johan Kanflo created the AAduino, a clone so compact that it occupies the place of a traditional AA battery. Up to now, Kanflo had been using Nathan Chantrell's Tiny328, but the format was not entirely suitable for his needs. The AAduino has two Keystone terminals that act as positive and negative, an RFM69C module, and there is also room to add two DS18B20 temperature sensors, along with an indicator LED. Kanflo configured the 328p to run at 8 MHz, a detail that helps extend the life of AA batteries. The truth is that the available energy forces it to operate slightly outside the recommended specifications, but nothing stops you from "lowering" the 328p to 4 MHz and seeing how it behaves.
Kanflo decided to publish the code, the circuit, and the bill of materials on GitHub, so anyone interested has the possibility to modify and create their own AAduino. I imagine it will be a matter of time before some Chinese manufacturer decides to flood eBay with this design, but if Kanflo can put it on sale on his own, welcome.
