RGB power and disk indicator for your PC

Ah, the humble power LED. Despite the RGB craze in the last few generations of PC hardware, the power and disk LEDs have been largely forgotten, blinking away in only one (or sometimes two) colors. But fear not, my fellow RGB fiends: I have the solution for you.

My fancy power LED has the following features:

• RGB, obviously
• One LED for both disk and power, taking advantage of color changes to indicate status
• Sleep status taking full advantage of RGB to bring attention to your PC even when you're not using it
• Animations for both extended disk activity and the aforementioned sleep status
• Extensive customization potential. I'll describe the basics of making the system work, and you can customize it with far more functionality as you desire

So let's get to it!

Hardware

To make this project work, you will need the following components:

• One or more 5mm RGB LEDs -- depending on your computer case's design. My Corsair Obsidian 750D has two LEDs flanking the power button.
• An Arduino with USB cable for controlling the LED
• 4-conductor RGB wire to connect the LEDs to the Arduino
• 3x 330 ohm resistor, one for each channel
• 1x 1K ohm resistor for use as a pull-down
• 4N27 Optocoupler for safely obtaining the disk activity signal from the motherboard
• Breadboard or circuit board for holding the components together

Principle of operation

Instead of connecting your LED(s) to the motherboard's power and disk headers directly, they will be connected to an Arduino that has full control over the color. The Arduino plugs into an onboard USB port which powers it when the computer is on or asleep (or increasingly, even when powered off). The motherboard's HDD LED header is connected to the optocoupler which then allows the Arduino to change the LED's color based on disk activity independently of the operating system running on the computer.

Wiring

Software