since i'm a bit crazy about electronics (and Erik is too), soon the idea came up to somehow funk up a rabbit. we need an electronic rabbit! the plan was to use many many leds of different colors to illuminate the wooden rabbit. colors were chosen to be bright red and blue, and to keep the project at a reasonable level, the number of leds was reduced to 64. in fact i then used only 63 of them, otherwise two leds of the same color would have been side by side. the "eye" of the rabbit caused that, you will see it on the photo to the left (click on it to enlarge).

the electronics itself is rather quick and dirty (i did not have much time). it uses a atmel atmega8 controller. at the bottom of the page there is a link to the schematic if you want to have a look. for the atmega8 circuit there's nothing special. i just left out the crystal, because the internal 8 mhz oscillator is more than enough for what i wanted to do here. i added a small reset network as well as a connector for in circuit programming. if you have a look at the schematic, you will notice, that the atmega8 lacks of enough pins to drive all the 63 leds. i got around this by using serial shift registers (74HC594D) for getting 63 outputs. in fact i used only the SPI, which is PB3 (serial output), PB5 (serial clock) and PB2 (shift register clock). the SPI is clocked with 4 MHz. this allows for very very quick updates of all those leds!

because the 75HC594D do not deliver enough current to drive eight leds each at full power, i decided to pump up the thing a bit by using some ULN2003AD. they can deliver up to 500 mA per channel. this is enough for even driving lamps instead of leds! anyway i put all those components together on a pcb and soldered a lot of wires to each of those leds. a big battery pack was added behind the rabbit shape. it was enough to drive the circuit for many hours during the wedding and even the days after.

now the fun part of this could start: the software! the full source code you can find along with some other files in the link section at the bottom of this page. the code is written in C. i used WinAVR for compiling the code on a windows system. there's not much to say about the code - it's pretty straightforward. i used the builtin SPI module of the microcontroller to send out the bytes for the shift registers. this is done in function SetLED(). everything else is just defining some nifty patterns and then calling them with different parameters from the main function. have a look for yourself, it's no real magic inside :)