On 24/03/18 10:08, Andy Burns wrote:
I've replaced the motherboard in a PC with a small SBC which has an
intel 9-pin front panel connector[1] rather than just a bunch of header
pins for LEDs and switches like a normal motherboard, the connector pins
are labelled in the board's own manual[2] as

1 HD_LED_P
2 PWR_P/SLP_N
3 HD_LED_N
4 PWR_N/SLP_P
5 RST_SW_N
6 PWR_SW_P
7 RST_SW_P
8 PWR_SW_N
9 UNUSED

so the power LED is between pins 2 and 4, and rather than a single
on/off LED, it offers the ability to use a bi-colour LED.

The way they're labelled PWR+/SLP- and PWR-/SLP+ I assumed it required a
2-pin LED with red/green wired in inverse parallel, such as

https://www.maplin.co.uk/p/twopin-qy83e

I bought one, it lights up green when power is on, but not red when
power is off (by reversing the connections I can make it light up red
when on, but still not green when off, so it isn't a case of the LED
being half dead).

Presumably this means in reality it requires a 3-pin LED, such as

https://www.maplin.co.uk/p/threepin-cj53h


Nope, it's a 2-pin. LED is driven across the outputs.


5v ---+----+
| |
R R
| |
| |
pin 2------+-----.
| |
| LED
| |
pin 4 +----------'


--
Adrian C