Mini-Itx

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Anybody using mini-itx with XP embedded?

I'm looking for a hardware/software switch to allow the MB to be always on -
ie. boots up as soon as power received - i.e. headless remote operation,
always on.



Re: Mini-Itx
Quoted text here. Click to load it

I believe that's a CMOS setup option.

Re: Mini-Itx
Quoted text here. Click to load it
on -
Quoted text here. Click to load it

The BIOS has an 'AC Loss Auto Restart' option. This will make the system
auto-start in an event of power loss while it was on, but if someone shuts
down the system properly, a power cycle will not start the system.

Rob



Re: Mini-Itx
Quoted text here. Click to load it

Ah. In that case, there's no direct way to do it, because I can tell
you from (silly) experience that jumpering the power button connector
doesn't make the board start up automatically. Actually, it's
weird-sometimes it will, sometimes it won't. I found this out because
I wired an Epia board into a custom housing with an external power
button, and didn't realize that some SOB had put a NC button in the
drawer where the NO buttons go. Took a LOT of head-scratching before I
worked out what was going on.

I would suggest making a simple active-low one-shot with a 555 powered
from the 5V standby line, to ping the power button for maybe 1s when
power is applied.

Re: Mini-Itx
Quoted text here. Click to load it

We solved this problem with our Thin Client

http://www.jkmicro.com/products/thinclient.html

by putting a PIC processor in the power supply.
The PIC sequences the voltages, provides a
watchdog function and provides a positive power
on boot (depending on jumper settings).



Re: Mini-Itx
Quoted text here. Click to load it

Wire an ATX power header to an AT power supply.

Quoted text here. Click to load it

This remind me of the big boys ways of solving problems.

1. Microsoft gives annoying pop-ups on internet explorer.  It solves
the problem with another annoying MSN adv. bar to block the pop-ups.
I would prefer a configuration option to stop pop-ups.

2. Intel gives ATX power switch.  You solves the problem with another
micro to power sequence it.  I would prefer to go back to AT power and
declare that ATX power was a big mistake.

Re: Mini-Itx
Quoted text here. Click to load it

Sigh.  I was happy with AT power supplies, and
I don't particularly enjoy sticking processors
in power supplies.  The reality is that you can't
outsmart anything with a couple diodes and a
resistor any more so we're stuck with somewhat
inelegant but cost-effective solutions.



Re: Mini-Itx
Quoted text here. Click to load it

I thought that a "Power Good" signal was output by *all* ATX and AT
PSUs.  Can't this be used to turn the Mobo on?  I expect it would
require a jumper or maybe even an inverter, but that is a lot simpler
than an MCU.  

--

Rick "rickman" Collins

snipped-for-privacy@XYarius.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Mini-Itx
Quoted text here. Click to load it

You missed the top part of the thread.  The original
issue was making sure that the machine would always
power up when input power came up, whether or not the
user did a shutdown.







Re: Mini-Itx
Quoted text here. Click to load it

I *do* understand that.  But the power good signal can be used to
control the power on button.  There is a standby supply that can provide
voltage to control a simple circuit that will use the power good signal
to activate the power on button.  As long as power good is not asserted,
the power on button should be asserted.  When power good comes up, the
power on button can be released.  

If the Power Good signal is high true, this circuit would be two
transistors.  If the Power Good signal is low true, this circuit can be
*one* transistor.  Quite a bit simpler than an MCU!  

--

Rick "rickman" Collins

snipped-for-privacy@XYarius.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Mini-Itx
Quoted text here. Click to load it

I should have know better than to bother a reply
to you.  I don't recall all the details, but I
do know that what you propose didn't work reliably.
That plus the fact that we needed a watchdog forced
the MCU issue.



Re: Mini-Itx


Quoted text here. Click to load it
provide
signal
asserted,

Ain't gonna work, at least not reliably.  There are allot of power
supplies out there that just have the PwrGd connected directly to the 5V
sources in the supply.  I'm not saying that's a good thing, just saying
that's the way it is.

Quoted text here. Click to load it
be

Really.....no passives needed?  It's clear that you don't even know
whether PwrGd is active high or low, I hope the OP sees the big red flag
on that.



Re: Mini-Itx
Quoted text here. Click to load it

If that is true, then the supply is not in spec.  

Quoted text here. Click to load it

Why does it matter if I know the polarity of Power Good.  Or are just
trying to be insulting?  I do know that the power on button is pulled
high with a resistor so that you can parallel the switch with another
switch of any sort.  I expect the power good signal to be high true, but
I don't recall what the spec says and I don't assume *anything* when it
comes to the PC.  

--

Rick "rickman" Collins

snipped-for-privacy@XYarius.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Mini-Itx
Quoted text here. Click to load it

It might be better to combine ATX 5VSTBY and a 5V source from the mobo
that's only on when in power-up state. Like the 5V that's available on the
extra USB headers on many ITX boards. Or the +5V that powers the keyboard.
When +5VSTBY is present and the USB header +5V is not,  then after 500ms
trigger the power button.

Rob



Re: Mini-Itx
Quoted text here. Click to load it

Argh! No! Not an RC power strobe! :)

Re: Mini-Itx
Quoted text here. Click to load it


There is of course no such thing as "The BIOS" in PCs any more.
There's lots of variance, and one of the little details that varies is
what options you have on "AC power loss restart".  Quite some BIOSes
offer a three-way selection: "never", "last state" and "always start".

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Re: Mini-Itx
Quoted text here. Click to load it

But there are definitely preferential relationships between specific
mobo or chipset vendors and specific BIOS vendors, and the context of
the discussion implies that we are talking very specifically about
Via's Epia series of motherboards (see
http://www.viavpsd.com/product/index.jsp ). These use an Award BIOS,
and a specific subset of the Award BIOS at that.

Re: Mini-Itx

Quoted text here. Click to load it

You can use cheap external modem powered from the same mains as headless
computer.  As soon as power comes up, the DTR signal gets active
indicating that external power is present and modem is ready (which might
or might not be of value in the case).

   Vadim

Re: Mini-Itx

Quoted text here. Click to load it

yes


LOL no !

Quoted text here. Click to load it

Bios "power on after power fail"

Pozdrawiam.
--
RusH   //
 http://pulse.pdi.net/~rush/qv30 /
We've slightly trimmed the long signature. Click to see the full one.

Site Timeline