As I've calculated in the previous log, around 70% of the total power consumption of this project comes from just the driving of the LED. The choice of protocol will have an enormous impact on battery life. My first choice was to use the NEC protocol. Let's see if we can do better.

Let's look at protocols supported be the Arduino-IRemote library. We'll be using a 33% duty cycle (9μs LED on time).

Let's start with the Denon protocol. Out of the available 14 bits 2 will be used for a checksum. This leaves us with only 12 bits for the password. 4000 combinations is not much, but for this project it should be enough.