As the title says, [Josť Faria] added the ability to adjust his keyboard backlight based on ambient light levels. But thatís just one of the things he did during his hacking extravaganza with this Razer BlackWidow Ultimate.
When he first received the peripheral he didnít like the blue LEDs used as backlights. So he removed all of them and put in white ones. He doesnít talk too much about that but weíd image it was a ton of work. The new color was pleasing, but then the ability to adjust their brightness started to irritate him. There are four predefined levels and thatís all you get. Even the GUI which has a slider for adjustment couldnít go outside of those levels.
His solution was to augment the controller with his own. He patched in an AVR chip to the transistor which controls the low side of the LED circuits. While at it he also noticed that the keyboard case was actually translucent. This let him hide a photosensor inside which automatically adjusts the light levels. But he did it in a way that still allows him to use the original functionality with the flip of a switch. See for yourself after the break.

http://hackaday.com/2013/05/11/auto-...ard-backlight/