I haved use a microcontroller to setup my lighting using PWM to drive LED's. I am a computer engineer and for those with relevant knowledge this is quite a simple project. PWM stands for Pulse Width Modulation and is basically a way for a simple digital output to affect the brightness of the LED by switching it off and on VERY fast (100's of times a second) the length of on time vs the length of off time is seen by our eyes as reduced brightness but because its so fast we cant see the "flicker".
I used one of these Parts & Kits for Arduino Online, Buy Microcontroller Boards, Electronic Components for Arduino - LeoStick (Arduino Compatible) - Freetronics as the controller and 3 of these Parts & Kits for Arduino Online, Buy Microcontroller Boards, Electronic Components for Arduino - NDRIVE: N-MOSFET Driver / Output Module - Freetronics to control the LED's
The scuff, front and rear LED's are controlled by separate driver modules and are thus controllable independently. The scuff only pulsates while the door is open. The front footwell (under dash) and rear footwell (under front seats) LED's fade in (get brighter then stay on full brightness) quickly when the door opens then fade out slowly to full off after 60 secs (at the moment rears fade out after 20 secs). If the ignition is set to ACC or ON the front LED's only fade out to about 20% brightness and stay on rather than fading out completely. When the ignition is turned off again the front and rear fades back in to full brightness.
The only inputs to the AVR are drivers door, passenger door and a "hot on ACC & ON" signals. Also need "always on power" for the leostick itself via a 5V regulator.
Beauty of using the AVR is I can change the programming later if I decide I dont like particular settings (e.g. brightness and timings). Also can add extra inputs and output drivers for other uses.
Here is a vid of my pulsating scuff (looks wicked) and driver footwell. BTW the scuff plate came from exLEDshop.com and and is just a basic led light that is normally connected to the door switches and so is either on or off, it does NOT pulsate by itself. This vid does not show footwell LEDs fading in or dimming though.
I may put together more details if there is interest in the project.