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

And that I need to split the ground from e.g. the hard disk LED cathode
pin to feed the power LED's common cathode, the labelling feels wrong
though ... would you have read it the way I did initially?



[1] http://www.formfactors.org/developer%5Cspecs%5Ca2928604.pdf
[2] http://download.udoo.org/files/UDOO_X86/Doc/UDOO_X86_MANUAL.pdf

Could you not sort this on the current led with diodes?
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Andy Burns" wrote in message
...
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

And that I need to split the ground from e.g. the hard disk LED cathode
pin to feed the power LED's common cathode, the labelling feels wrong
though ... would you have read it the way I did initially?



[1] http://www.formfactors.org/developer%5Cspecs%5Ca2928604.pdf
[2] http://download.udoo.org/files/UDOO_X86/Doc/UDOO_X86_MANUAL.pdf

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

On 24/03/2018 11:31, Adrian Caspersz wrote:
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 +----------'


Perhaps there's a short to ground on pin 4.
--
Dave W

On 24/03/18 10:08, Andy Burns wrote:

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).

Another thought ...

That red might only be visible in standby/sleep state.

When the board is actually powered off, the LED is naturally devoid of
electrons and doesn't light.

--
Adrian C

Brian Gaff wrote:

Could you not sort this on the current led with diodes?

I don't think so, because there are only two pins which I expected to be
pos and neg in one stage, and neg and pos in the other state ...

Adrian Caspersz wrote:

That red might only be visible in standby/sleep state.

That's what I want.

When the board is actually powered off, the LED is naturally devoid of
electrons and doesn't light.

The SBC does actually have a surface mounted two-colour LED, which works
as expected, provided the external power brick is connected, I want a
case LED to follow what the on-board one does ...

Dave W wrote:

Perhaps there's a short to ground on pin 4.

I'll check, but if so I'd expect it would drag the on-board "off" light
down to ground and it not work either, but it does work.

On Saturday, 24 March 2018 10:08:59 UTC, 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

And that I need to split the ground from e.g. the hard disk LED cathode
pin to feed the power LED's common cathode, the labelling feels wrong
though ... would you have read it the way I did initially?



[1] http://www.formfactors.org/developer%5Cspecs%5Ca2928604.pdf
[2] http://download.udoo.org/files/UDOO_X86/Doc/UDOO_X86_MANUAL.pdf

TBH I don't see much use in these lights unless the PC is in a noisy environment. I cant tell when power is on & when hdd is accessing.


NT

tabbypurr wrote:

TBH I don't see much use in these lights unless the PC is in a noisy
environment. I cant tell when power is on & when hdd is accessing.
This is a fanless SBC, with onboard eMMC, which runs off a 12V power
brick, so it really is silent ...

On Saturday, 24 March 2018 13:03:31 UTC, Andy Burns wrote:
tabbypurr wrote:

TBH I don't see much use in these lights unless the PC is in a noisy
environment. I cant tell when power is on & when hdd is accessing.
This is a fanless SBC, with onboard eMMC, which runs off a 12V power
brick, so it really is silent ...

eh, it's all your fault for coming up with the one exception

I don't think the LEDs will come to any harm if you just stick them on the relevant pins and see what works.


NT

Adrian Caspersz wrote:

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


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

The manual does indeed say each pin has a pull-up resistor, and I would
expect it to pull down one pin or the other depending which colour it
want to show.

But why would the LED show one colour when on, but _not_ the other
colour when off? Given that both colours work, depending on which way
round I connect it ...

On 24/03/18 13:33, Andy Burns wrote:
Adrian Caspersz wrote:

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


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

The manual does indeed say each pin has a pull-up resistor, and I would
expect it to pull down one pin or the other depending which colour it
want to show.

But why would the LED show one colour when on, but _not_ the other
colour when off?Â* Given that both colours work, depending on which way
round I connect it ...


Maybe the onboard LED you are comparing against (which is not documented
in the manual!), is perhaps just showing a 'power connected'
confirmation that you have your external power brick attached - it's not
actually sleep.

I have equipment here that works like that.

[Apologies if you already know this ] Sleep state is a thing a
computer is placed into, if the OS configured by the OS and/or BIOS.

System Power States

https://msdn.microsoft.com/en-us/lib...(v=vs.85).aspx

--
Adrian C

On Sat, 24 Mar 2018 13:33:13 +0000, Andy Burns
wrote:

Adrian Caspersz wrote:

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


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

The manual does indeed say each pin has a pull-up resistor, and I would
expect it to pull down one pin or the other depending which colour it
want to show.

But why would the LED show one colour when on, but _not_ the other
colour when off? Given that both colours work, depending on which way
round I connect it ...

2 PWR_P/SLP_N
4 PWR_N/SLP_P

Power on - one colour
Sleep - other colour
Off - no power so no led at all

?

Avpx



--
A good bookshop is just a genteel Black Hole that knows how to
read.
(Guards! Guards!)
14:05:01 up 16 days, 5:29, 11 users, load average: 0.74, 0.76, 0.75

wrote:

I don't think the LEDs will come to any harm if you just stick them
on the relevant pins and see what works.
Hmmm, have probed them with a multimeter ...

When the machine is on, the on-board LED is green, pin 2 is at +5V and
pin4 is at 0V, so the green external LED shows "on" as expected.

When the machine is asleep (or is shutdown) the on-board LED is amber
and both pins 2 and 4 are are at +5V which explains why neither colour
of the external LED across them is lit.

I can't see how the external LED can show red for "off" when connected
as per the manual. There's no setting in BIOS to let machine know it
has a bi-colour LED available.

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

And that I need to split the ground from e.g. the hard disk LED cathode
pin to feed the power LED's common cathode, the labelling feels wrong
though ... would you have read it the way I did initially?


I'm sure you've got the right LED. Are you sure you're identifying
pins 2 & 4 correctly, along the side of the connector rather than across
it? I've got that wrong more than once before. Pins 2 & 3 should give
the readings you describe in your other post. That is, the second row
*across* the connector.

--

Roger Hayter

Andy Burns wrote:
When the machine is on, the on-board LED is green, pin 2 is at +5V and
pin4 is at 0V, so the green external LED shows "on" as expected.

When the machine is asleep (or is shutdown) the on-board LED is amber
and both pins 2 and 4 are are at +5V which explains why neither colour
of the external LED across them is lit.

I can't see how the external LED can show red for "off" when connected
as per the manual. There's no setting in BIOS to let machine know it
has a bi-colour LED available.

The Intel doc only describes green and yellow states, never red.
The manual says:

FP PWR_P/SLP_N: Power/Sleep messaging LED terminal 1 with 510Ω pull-up
resistor to +5V_A voltage. Connect it to an extremity of a dual-color power
LED for power ON/OF, sleep and message waiting signaling. Please refer to Intel®
Front Panel I/O connectivity Design Guide, chapter 2.2.4, for LED
functionalities and signal meaning.
FP PWR_N/SLP_P: Power/Sleep messaging LED terminal 2 with 510Ω pull-up
resistor to +5V_A voltage. Connect it to the other extremity of the
dual-color power LED above mentioned

So it seems you can attach an R+G LED and get:
R=off G=on = green: power on
R=on G=on = yellow: sleep
R=off G=off = dark: off

The description agrees if there is a ground available, so a pin being pulled
up high turns the LED on. Though I would have expected an additional wire
on the connector for that, and the Intel doc suggests back to back G+Y LEDs.
Either way, you'll never get red.

If I pull up the schematic:
http://download.udoo.org/files/UDOO_...schematics.pdf
the signals are wired S3_LED (p4) and S5_LED (p2), with a 510ohm to +5V and
a MOSFET pulling low. They're driven from an STM32F100 microcontroller.
In ACPI terminology S3=sleep and S5=soft-off. I would therefore assume:

S3_LED=low S5_LED=low: machine on, LED=green
S3_LED=high S5_LED=low: sleep, LED=yellow
S3_LED=low S5_LED=high: soft-off, LED=red
S3_LED=high S5_LED=high: hard-off, LED=dark

which implies an R-G LED with separate ground, rather than an Intel
back-to-back G-Y LED.

Since it's firmware controlled, using either would be possible (with
different results).

Strangely, the on-board LED has a completely different setup that appears to
be based on reset and power rail state, rather than software controlled. So
its behaviour could well differ.

Theo

Theo wrote:

The Intel doc only describes green and yellow states, never red.

I think they're assuming and amber+green LED, that's certainly what's
onboard, you can see the individual dies on the LED, and it isn't mixing
red plus green to get yellow, whereas I have a red+green LED.

The manual says:

FP PWR_P/SLP_N: Power/Sleep messaging LED terminal 1 with 510Ω pull-up
resistor to +5V_A voltage. Connect it to an extremity of a dual-color power
LED for power ON/OF, sleep and message waiting signaling. Please refer to Intel®
Front Panel I/O connectivity Design Guide, chapter 2.2.4, for LED
functionalities and signal meaning.

It seems they're using the intel physical connector, but with different
meanings for the signals.

implies an R-G LED with separate ground, rather than an Intel
back-to-back G-Y LED.

Yes despite the doc, that's the conclusion I've come to; use a 3-pin
LED, connect the green anode to pin2 and red anode to pin4, and the
common cathode to a ground I can borrow from elsewhere (e.g. the HD LED
cathode)

then the green side will stay on all the time, the red will turn on when
the system is sleeping or shutdown, thereby mixing to give yellow, so
I'll get green or yellow, rather than green or red

Poor documentation though ...

Andy Burns wrote:

that's the conclusion I've come to; use a 3-pin
LED, connect the green anode to pin2 and red anode to pin4, and the
common cathode to a ground I can borrow from elsewhere (e.g. the HD LED
cathode)

then the green side will stay on all the time, the red will turn on when
the system is sleeping or shutdown, thereby mixing to give yellow, so
I'll get green or yellow

I found a 3-pin amber + green LED in the parts box, and yes it works as
above, except amber+green is not very distinguishable from green alone,
so I'll buy a 3-pin red + green LED

Roger Hayter wrote:

Andy Burns wrote:

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

I'm sure you've got the right LED. Are you sure you're identifying
pins 2 & 4 correctly, along the side of the connector rather than across
it?

Well depends which way round you're viewing it, but the ones identified
in green as per this diagram.

http://www.fixya.com/uploads/images/B9BFA92.jpg

The disk LED, reset and power switches function OK.

I've got that wrong more than once before. Pins 2 & 3 should give
the readings you describe in your other post. That is, the second row
*across* the connector.

On Saturday, 24 March 2018 19:35:39 UTC, Andy Burns wrote:
Andy Burns wrote:

that's the conclusion I've come to; use a 3-pin
LED, connect the green anode to pin2 and red anode to pin4, and the
common cathode to a ground I can borrow from elsewhere (e.g. the HD LED
cathode)

then the green side will stay on all the time, the red will turn on when
the system is sleeping or shutdown, thereby mixing to give yellow, so
I'll get green or yellow

I found a 3-pin amber + green LED in the parts box, and yes it works as
above, except amber+green is not very distinguishable from green alone,
so I'll buy a 3-pin red + green LED

if you added resistance on the green side that would help with the colour change


NT

Andy Burns wrote:

Roger Hayter wrote:

Andy Burns wrote:

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

I'm sure you've got the right LED. Are you sure you're identifying
pins 2 & 4 correctly, along the side of the connector rather than across
it?

Well depends which way round you're viewing it, but the ones identified
in green as per this diagram.

http://www.fixya.com/uploads/images/B9BFA92.jpg

The disk LED, reset and power switches function OK.

I agree then that from your measurements the board simply doesn't do
what it says it should.





I've got that wrong more than once before. Pins 2 & 3 should give
the readings you describe in your other post. That is, the second row
*across* the connector.


--

Roger Hayter