Our new server had a few spare LEDs labeled S1, S2 and with a fan symbol on the front panel that apparently were made to be used with some extra hardware. Since I got that case for cheap I of course don’t have that certain piece of hardware so I decided to make my own to be able to control these LEDs. There was an open 8 pin cable so it was quite easy to figure out what it does by just probing it with an LED tester. Since I only needed 3 pins to control the LEDs I used an ATTiny85 for this board and decided to connect it to a spare internal USB header on the server’s main board. With the Digispark USB Library communication is quite easy to implement without any extra steps. I also connected the extra button in the front panel to the reset pin of the ATTiny so I can reprogram it without opening the case if needed.
The schematics are basically the same as for the USBTiny85 with an additional ICSP header to make initial programming easier, a 4-pin header for the usb cable and of course the header for the front panel plug. Schematics and board design below, also some pictures of the finished product!