How to make a laptop start up when ext power is applied?

[Peter]

I need to make a laptop start up when external power is applied,
without having to press the power button.

Actually it will be an Asus EEE PC running Linux but that is probably
irrelevant.

Is there something they do in computer showrooms, to make them all
start up in the morning?

 

[Pegasus [MVP]]

I need to make a laptop start up when external power is applied,
without having to press the power button.

Actually it will be an Asus EEE PC running Linux but that is probably
irrelevant.

Is there something they do in computer showrooms, to make them all
start up in the morning?

The BIOS of some desktop PCs has a setting that allows an automatic startup
setting. I have never seen it in laptops. Since your question is not in any
way related to Windows, I recommend you repost it in a hardware newsgroup.

 

[Shenan Stanley]

I need to make a laptop start up when external power is applied,
without having to press the power button.

Actually it will be an Asus EEE PC running Linux but that is
probably irrelevant.

Is there something they do in computer showrooms, to make them all
start up in the morning?

Hardware dependent.

If the system has a BIOS setting that controls the power settings - it can
be done. If it does not - it cannot be done.

 

[larwe]

Is there something they do in computer showrooms, to make them all
start up in the morning?

Leave them on all night, or BIOS setting, or come around and switch on
in the morning - that's how the showrooms do it. If no BIOS setting is
available - often the case on laptops - then you need to build a
little circuit that pulses the power control line when the standby
voltage appears. I've done this many times when repurposing laptops to
use as the core of an embedded system. I used an 8-pin PIC because I
had them lying around. A 555 would do just as well.

 

[Peter]

Leave them on all night, or BIOS setting, or come around and switch on
in the morning - that's how the showrooms do it. If no BIOS setting is
available - often the case on laptops - then you need to build a
little circuit that pulses the power control line when the standby
voltage appears. I've done this many times when repurposing laptops to
use as the core of an embedded system. I used an 8-pin PIC because I
had them lying around. A 555 would do just as well.

Very interesting - would you be able to post more details?

 

[larwe]

Very interesting - would you be able to post more details?

It's highly platform-specific, but here is the general principle:

When power is available, there will be a standby voltage present
somewhere on the board at all times, to support Wake-on-LAN, wake-on-
Bluetooth, etc. On a desktop PC, there is an explicit +5Vsby output
from the PSU. On a laptop, you either get lucky with the silk-
screening or you probe around the board with the machine switched off.
Start with the Vcc pin of any small microcontroller you can observe.
The line should also be available at any internal PCI, PCIe slot, I
believe.

IIRC when I had an Eee 2G Surf, it provided USB bus power at all times
when AC was present (to hell with the spec, full speed ahead, right?).
So that might be a convenient takeoff point if you have no luck
elsewhere - it won't be available when the unit is running off
battery, though.

The power button on a laptop is typically an active low input to some
kind of power management microcontroller. Pull it low, the machine
starts up. Unfortunately in most cases it is not enough to simply tie
that line low because holding the button low typically invokes an
emergency hard shutdown in the case where the main CPU is irrevocably
crashed.

So get your 8-pin PIC, or your 555 rigged as a one-shot. Configure it
so that as soon as power is applied, it will wait (say) 1 sec for
everything to stabilize, then pull the power-on line low for 500ms,
then release that line and go to sleep forever. Power the micro/555
from the standby voltage and connect the output to the power control
pin.

An RC might sometimes do the trick too, but I haven't found this to be
very reliable in the past (too iffy, especially if there is a brownout
or power glitch that leaves the PSU in its switched-off state, but the
RC charged above the Vil voltage of that control line).

 

[larwe]

If the system has a BIOS setting that controls the power settings - it can
be done.  If it does not - it cannot be done.

Inaccurate. You forget that this message was cross-posted to
comp.arch.embedded, where we don't need operating systems nor user
manuals, and any signal that can be physically accessed can be used,
even if it isn't brought out to a LED or pushbutton.

 

[larwe]

Very interesting - would you be able to post more details?

Actually I just re-read your post and I realize I may have
misinterpreted your skillset (based on the fact that I came across the
message in c.a.e I assumed you were an embedded person).

If you need actual design/building help, email me - the address is
valid.

 

[Shenan Stanley]

I need to make a laptop start up when external power is applied,
without having to press the power button.

Actually it will be an Asus EEE PC running Linux but that is
probably irrelevant.

Is there something they do in computer showrooms, to make them all
start up in the morning?

Hardware dependent.

If the system has a BIOS setting that controls the power settings -
it can be done. If it does not - it cannot be done.

Inaccurate. You forget that this message was cross-posted to
comp.arch.embedded, where we don't need operating systems nor user
manuals, and any signal that can be physically accessed can be used,
even if it isn't brought out to a LED or pushbutton.

No - I did not forget - I ignored and followed up on exactly what had been
given.

Without modification of the hardware, which a "computer showroom" mentioned
in the beginning of this posting would not do unless they did not want to
sell those particular laptops again, what I said is accurate.

It is *hardware dependent*. If the system has a BIOS setting that controls
the power settings - it can
be done. If it does not - it cannot be done.

Now - if the OP is intending to modify the hardware - well sure, it could be
done. Then again - why mention a 'computer showroom' if that is so - after
all, I have not seen a computer showroom that modified their systems
(especially laptops) in order to turn them on. They either left them on or
they had someone who worked there turn them on when the store opened.

 

[cs_posting]

No - I did not forget - I ignored and followed up on exactly what had been
given.

Without modification of the hardware, which a "computer showroom" mentioned
in the beginning of this posting would not do unless they did not want to
sell those particular laptops again, what I said is accurate.

It's not clear that a computer show room was the intended
application. I read it as the poster suggesting a situation where
people might already be doing something similar to what was needed for
unspecified application.

In a computer showroom, wake-on-lan might be a possibility. Just have
an pre-ATX box wired to the light switch that continually hits all
the machines with whatever traffic will wake them up.

Realistically though, I bet they leave them on all night - even in the
unlikely case that its store policy to shut them down, I bet they
usually get left on.

 

[Bruce Chambers]

That sounds like it's BIOS-dependant rather than
hardware-dependant. And BIOS is software, not hardware.

To be more accurate, the BIOS is "Firmware*, which makes it more
hardware-dependent than not.


--

Bruce Chambers

Help us help you:


http://support.microsoft.com/default.aspx/kb/555375

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safety deserve neither liberty nor safety. ~Benjamin Franklin

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killed a great many philosophers.
~ Denis Diderot

 

[larwe]

        To be more accurate, the BIOS is "Firmware*, which makes it more
hardware-dependent than not.

A hardware engineer won't generally make that distinction - to such a
person, chips are hardware and the bits stored within them are
software.

So, how many angels can dance on the head of a pin, anyway?

 

[Peter]

Actually I just re-read your post and I realize I may have
misinterpreted your skillset (based on the fact that I came across the
message in c.a.e I assumed you were an embedded person).

If you need actual design/building help, email me - the address is
valid.

I am quite experienced hardware/software developer, ex 8048, 8051,
z80, z180, z280, 80x86, H8/300, but don't like to dismantle laptops
because getting them back together again can be tricky

Also I know very little about PC architecture - beyond constructing
loads of PCs from standard parts.

The application in this case is indeed an embedded comms controller,
interfacing to a satellite phone and outputting some data on the VGA
output.

Thank you for posting the other stuff - very useful.

 

[TTman]

I need to make a laptop start up when external power is applied,
without having to press the power button.

Actually it will be an Asus EEE PC running Linux but that is probably
irrelevant.

Is there something they do in computer showrooms, to make them all
start up in the morning?

I did it on a real PC with a capacitor across the startup button....... no
reason it shouldn't work for a laptop...

 

[larwe]

I did it on a real PC with a capacitor across the startup button....... no
reason it shouldn't work for a laptop...

It's not always reliable - see other post.

 

[larwe]

I am quite experienced hardware/software developer, ex 8048, 8051,

Good, I guessed right the first time then

z80, z180, z280, 80x86, H8/300, but don't like to dismantle laptops
because getting them back together again can be tricky

The Eee is very simple though, not challenging to disassemble at all.
Lots of people are using them for robotics and other applications.
It's a very cheap SBC for the performance, especially the older/
smaller models which can now be found on eBay under $120 sometimes.

Thank you for posting the other stuff - very useful.

Enjoy

 

[dbr]

Peter - check the bios for power-on options, ie what happens when power is
turned on. Usually there is a message on the screen when the computer is first
booting that says, roughly, "press xxx for setup".

Hul

I am quite experienced hardware/software developer, ex 8048, 8051,
z80, z180, z280, 80x86, H8/300, but don't like to dismantle laptops
because getting them back together again can be tricky

Also I know very little about PC architecture - beyond constructing
loads of PCs from standard parts.

 

[David Wilson]

Is there something they do in computer showrooms, to make them all
start up in the morning?

If I were in that situation, I would use the RTC and BIOS turn on time
setting. No hardware mods required. This has been a standard feature
of PC BIOS setup programs for a very long time. Of course if you need
anything more flexible you will need to use the ideas provided by the
other posters.

As an example, I checked my old NEC Versa VXi and it has this
capability in the Power Management Setup screen.