RPN Scientific Firmware for the Spikenzielabs Calculator Kit

[jklsadf]

With regards to the battery life, the original firmware turned off the calculator automatically to preserve battery life (I think within less than a minute after the last key press). As you noted, the backlit display draws a lot of power. The soft-latching power switch is quite effective in the off state, and draws almost no power when off. I measured it once, but don't remember the exact number off the top of my head.

I personally have the calculator plugged in to and powered from the USB-to-serial converter all the time, so it hasn't been an issue for me to have it on all the time. (The form-factor with the tilted screen really is ideal for desktop use, and makes the screen a lot easier to see than most "pocket" calculators with a flat screen.) I haven't really looked into trying to put the microcontroller into low power modes, since the backlight is probably one of the biggest power draws. I do turn off the backlight while doing calculations, but that's more of an indicator that a button was pressed and calculation is in progress. An auto power off would be a nice optional feature to have, although I personally like having it stay on all the time.