I am still very new and learning all of this. I am trying to make an energy efficient IR emitter/sensor device that will record the time of an IR beam break. It needs to run for several months. I am considering using the adafruit data logger shield to keep track of time and record the data on an SD card. I know arduino can be power hungry so I was considering using either an Arduino Pro Mini 328 or ATtiny85, but I don't really know if these are appropriate, capable, energy efficient, etc. I will appreciate any and all input about what materials are best here. Thanks!