How does a CarPC shutdown?

**walttoinfiniti** · 07-26-2006, 06:03 PM

I'm wanting to design a Power Supply controller, since none I've seen meet my needs. I have a question that I need to get clear in my mind and maybe someone can clarify it for me.
A PS has power applied to it all the time. But for it to turn on, the PS controller has to send a signal to the motherboard, (called the "ATX power on switch", on my MB896 board). This is normally a pair of wires that connected to a small plug that is pushed onto a header.

I'm not clear about what happens when the signal goes away. If it controls the PS, I would expect the PC to just turn off immediately, but it instead causes the PC to shutdown in an orderly fashion.

How does this work?

Thanks,
Walt

**DarquePervert** · 07-26-2006, 06:19 PM

The motherboard initiates a shutdown from the OS (assuming it can handle ACPI commands). For WindozeXP, this is the same as Start > Turn Off Computer > Turn Off (by default). The behavior can be changed in the Power control panel.

I'm curious about why the currect crop of PSUs and SDCs don't meet your needs....

**kamikaze2112** · 07-26-2006, 11:41 PM

Originally Posted by walttoinfiniti

I'm wanting to design a Power Supply controller, since none I've seen meet my needs. I have a question that I need to get clear in my mind and maybe someone can clarify it for me.
A PS has power applied to it all the time. But for it to turn on, the PS controller has to send a signal to the motherboard, (called the "ATX power on switch", on my MB896 board). This is normally a pair of wires that connected to a small plug that is pushed onto a header.

I'm not clear about what happens when the signal goes away. If it controls the PS, I would expect the PC to just turn off immediately, but it instead causes the PC to shutdown in an orderly fashion.

How does this work?

Thanks,
Walt

I think you may be misunderstanding the power on header. With a standard desktop system the mobo draws power from the power supply all the time as long as it's plugged in and the switch on the PS is on. when you hit that switch, all you are doing is closing a circut that tells the power supply to start powering up the computer. It doesn't have power running thru it all the time (like an old AT system, that has a hard on/off switch). With the current carpc power supplies, they sense for voltage on a remote lead, kinda line an amplifier, then the startup/shutdown controller basically simulates the pushing of the power button by closing the circut. When it goes to shut the machine down, it does the same thing, only instead of the power supply telling the computer to startup, windows shuts down, goes into standby, or hibernates, baseed on the settings you choose in the power options.

I have an M2-ATX and i love it. The default shutdown timings didn't exactly meet my needs, but luckily i found a member of these boards (Piabu) who sent me a modified PIC with some custom shutdown timings on it.

**walttoinfiniti** · 07-27-2006, 07:22 PM

Been getting more info, and I think that the momentary signal on the header does not go directly to the Power Supply, but just to the motherboard. The motherboard when it gets this will grd. the pin labelled "PS-ON" on the large 20 pin PS connector, which turns on the Power Supply.

So my guess is that sending another signal to the motherboard will initiate a shutdown to windows, which will then remove the grd from "PS-ON".

Not sure, but will try to do some test this weekend.

What I want that I can't get now is instant On from a controller. Don't need to wait 10 sec to turn on the PC. PC works fine while starting car.

I also want to be able to trigger the PC on from a Pulse signal, (Door Unlock)
or Interior Lights being turned on. PC will run for about 10 min. and then shut down, unless Ign/Acc switch is on.

If door is left open, and no Ign/Acc then PC will still turn off in 10 min.

Normally PC will remain on for 60 mins after exiting car, but by pressing the door lock 3 times within 3 sec. PC will be shutdown immediately.

Also want to incorporate a 4 hour shutdown mode for long dining or shopping experiences.
(guess I could use a single long Lock signal, but don't know if it works that way)

I am about 80 percent finished with the logic. I'm using a PIC 16F877. Just waiting on a programmer and some other hardware.

**zootjeff** · 07-28-2006, 12:34 PM

Originally Posted by walttoinfiniti

Been getting more info, and I think that the momentary signal on the header does not go directly to the Power Supply, but just to the motherboard. The motherboard when it gets this will grd. the pin labelled "PS-ON" on the large 20 pin PS connector, which turns on the Power Supply.

So my guess is that sending another signal to the motherboard will initiate a shutdown to windows, which will then remove the grd from "PS-ON".

Not sure, but will try to do some test this weekend.

What I want that I can't get now is instant On from a controller. Don't need to wait 10 sec to turn on the PC. PC works fine while starting car.

I also want to be able to trigger the PC on from a Pulse signal, (Door Unlock)
or Interior Lights being turned on. PC will run for about 10 min. and then shut down, unless Ign/Acc switch is on.

If door is left open, and no Ign/Acc then PC will still turn off in 10 min.

Normally PC will remain on for 60 mins after exiting car, but by pressing the door lock 3 times within 3 sec. PC will be shutdown immediately.

Also want to incorporate a 4 hour shutdown mode for long dining or shopping experiences.
(guess I could use a single long Lock signal, but don't know if it works that way)

I am about 80 percent finished with the logic. I'm using a PIC 16F877. Just waiting on a programmer and some other hardware.

Do you have 4 hours of running time on your battery? You must be powering a pretty small system..

**walttoinfiniti** · 07-29-2006, 02:53 PM

Here is a little more info that might be useful.

Ran a few test today and got the following results:

Test were run using a pushbutton to turn the PC On and Off. The cable on the OPUS 120 that normally goes to the motherboard header was left off.

On the OPUS 120W PS, when the Ign/Acc and the 12v Power are connected current draw is .18 amps. This is what I consider to be the OPUS On mode.

If the Ign/Acc input is not tied together then the mode changes to what I call Standby, and the current is very much lower.

When going from Standby to On there is a 10 sec startup delay and during this period, the OPUS cannot power up the PC.

My controller will keep the OPUS On for about 12 hours, before switching it to Standby. This will limit the initial 10 sec delay to only 1 time during a 12 hour period.
The OPUS will only supply the Power to the PC and my Controller will manage the PC On/Off.

Actually 4 hours was chosen a estimate. It might be more or less. I have a small 12v 12 amp battery that I will use to see how long it will sustain operation and use this as my final time. Since it is considerably smaller than the car battery, it will provide a margin of safety.

**walttoinfiniti** · 07-29-2006, 05:48 PM

By the way I am running a intel p4 m series. The Processor is either a 1.5 or 1.8 Celeron. These are the Processors that are used in laptops. So if I can get 4 hours from a laptop battery on my laptop I surely should be able to get this and more with a car battery and no display.

Walt