Three state power LED

[Riado]

Hi all,

I would really appreciate your help in this matter if you can, as I looked in a lot of areas for many hours and couldn't find the right information.

I need to build a small circuit board to indicate a power ON state (solid) and S3 standby state (fading/flashing), and need the LED to turn off when computer is in OFF state.

I have found a diagram by japala which nearly does what I want with the exception that it will also fade when computer in OFF state:

How do I differentiate between standby and OFF states?

Thanks again for looking into this.
Riado

 

[Riado]

After some digging further, I found out that some motherboards will have a feature to control the supply of +5v through the USB header when in OFF state. This kind of control is either as a jumper on the motherboard or as an option in the BIOS.

In S3 standby state the USB header should always supply +5v, or at least it should be controlled via the OS or the BIOS.

This means I might be able to take power from the USB header instead of +5vsb.

I will do further testing and let you know.

Riado