Basic Stamp to control my Car-Puter - Page 2

digitallexus · 04-05-2003, 02:44 AM

You would have to check your motherboard to see if it stops pulling the PS_ON line low if it sees power_good go low.

I know my Epia M9000 doesn't even use the power good line.

The ATX PS Spec says that the power supply should assert this low only when the voltage rails are falling to zero.

Telek · 04-06-2003, 08:29 AM

Well according to the ATX PS Spec that you provided, the PowerGood line is supposed to be dropped at least 1ms before voltage levels fall below tolerance (which is typically only 5% below rated output), which means that any ATX-compliant motherboard that has a self-preservation instinct should shut itself off to avoid brownout damage. Thus if we were to artificially drop the PowerGood line then the motherboard should instantly shut off. I suppose though, as you said, not all motherboards use the PowerGood line, but for those that do this might be a neat way to avoid using a relay.

mp3hombre · 04-06-2003, 10:59 AM

I agree with digitallexus, a PIC is the way to go.
Another member is working on something similar, a PIC-controlled power supply/shutdown controller.

H e r e

Telek · 04-06-2003, 01:48 PM

Why is a PIC the way to go when it's like 2-4x as expensive as any other method of doing it not using one?

digitallexus · 04-06-2003, 03:16 PM

A programmable chip with multiple lines of input and output that only costs a few dollars at most? What's not to like?

The alternative is logic and timing chips which is going to be much more complex to design.

Telek · 04-06-2003, 05:52 PM

Well if anyone can post a simple schematic then I'd be (and I'm assuming everyone else would be as well) interested!

I have a simple setup that I think should work, using only 2 diodes, 2 caps, 2 resistors and 2 transistors which provides a basic delayed shutdown that should work. Super duper cheap and easy to implement. But it's not very versatile. Any more info on how to make the PIC setup work?