Basic Stamp to control my Car-Puter

amrit50 · 04-03-2003, 11:17 AM

I've noticed that some people on here are working w/ startup and shutdown controlers. I wotre and programmed a basic stamp to startup my computer, and shut it down 30 min after i get out, and also close my windows and sunroof for me. PM or email me or respond if you are interesed in some info.

Telek · 04-04-2003, 02:45 PM

why don't you post some info here so that everyone can read? How complicated is the setup?

amrit50 · 04-04-2003, 04:35 PM

it's really too much to post. You have to hook it up to a serial port, program it, and then run inputs and outputs all in a specific manner. If someone wants to have it done, i could do it for them.

Telek · 04-04-2003, 04:36 PM

can you at least summarize here?

how much would it cost?

amrit50 · 04-04-2003, 04:41 PM

The inputs consist of 12v + and -, and an ignition switch regulated down to 5v. The outputs all drive relays thru transistors on the stamp board. They turn the relays on and off. The schematic is quite involved. I would sell a kit for $150 that had the stamp pre-programmed w/ just wires coming out a plastic box that all get hooked up like an alarm... One to 12+, one to 12v-, one to the ignition, and one to the computer switch and one to the computer power suppy and one to the monitor (if you'd like) I make my monitor come on after the computer boots so that you don't ever see the booting. I have a the stamp power an inverter that goes straight to an ac standard computer power supply.

digitallexus · 04-05-2003, 12:48 AM

Basic Stamps are about $30-$50 depending on the version.

They're super easy to program. It's basic after all.

If you're looking for a cheap solution though, then a PIC is the better way to go. And frankly for simple applications like these, programming a little bit of assembly is not that much harder than basic.

Controlling relays with the stamp is dead simple. I used a uln2003a which is a high current transitor array chip. It contains 7 transistor controllers. It uses a darlington configuration (i.e 2 stacked transistors) for each channel for low power control of high current devices (like relays).

http://www-s.ti.com/sc/ds/uln2003a.pdf

It all depends on your skill level of course. If you have basic electronics knowledge and a basic programming skills, then this is an easy project.

Telek · 04-05-2003, 01:09 AM

This is really annoying now.

The thing is that there is already a relay on the PSU itself that can be used, so that we don't need a second one. It really shouldn't be that complicated to have a simple version, I don't know why noone has built and published an open-source shutdown controller that is easy to make yet. It can't be all that difficult.

I'm working on a spec right now, but unfortunately my limited knowledge of electronics is making it difficult to proceed, however if I get it working then I will integrate it with my version of the sproggy power supply.

amrit50 · 04-05-2003, 01:22 AM

Quote:

Originally posted by Telek
This is really annoying now.

The thing is that there is already a relay on the PSU itself that can be used, so that we don't need a second one. It really shouldn't be that complicated to have a simple version, I don't know why noone has built and published an open-source shutdown controller that is easy to make yet. It can't be all that difficult.

I'm working on a spec right now, but unfortunately my limited knowledge of electronics is making it difficult to proceed, however if I get it working then I will integrate it with my version of the sproggy power supply.

The PSU doesn't shut down? There is a DC power supply you can buy for $180 that does.

digitallexus · 04-05-2003, 01:31 AM

That's exactly what I did (using the existing sproggy relay).

There was nothing to it. One jumper from the p0 control line on the stamp to the uln2003, 12v to the uln2003, and a line from the uln2003 to the relay coil.

.........................12v
........................ |
........................ |
Stamp ------ p0 ------> uln2003 -----> sproggy relay

I don't have anything written down. I just have it wired up on a prototype board.

Telek · 04-05-2003, 01:38 AM

Sorry I was referring to the Sproggy DIY PSU design. I don't want to pay $200 for something that should cost less than half that.

Here's a dumb question: With ATX motherboards, if you turn off the PowerGood lead to the mobo, will it turn the mobo off?

If so, perhaps we couldjust use a transistor to control the PowerGood lead instead of using a relay?

That won't turn off power to peripherals like the hard drive, however the HD should power itself down after a small amount of inactivity which should limit the current used.

So could we just toggle the PowerGood or the PS_ON wires instead of having to toggle the main relay? This way we can also use the +5V rail for +5VSB as well, as long as you don't pull too much current you won't need to turn on a fan or anything and that way we can get rid of that addition and be able to supply full current...

This can't be a very difficult thing to do.

digitallexus · 04-05-2003, 01:54 AM

It depends on how the bios is configured, but by default you can turn off an ATX mb by pulling the PS_ON line low for 4 seconds.

If you already have the transistor to support PS_ON, then you can directly connect to the stamp (or pic).

digitallexus · 04-05-2003, 02:02 AM

You can't eliminate the relay completely. You need it to switch the high amp 12v source. A transistor can only handle a few hundred milliamps at best.

Telek · 04-05-2003, 02:16 AM

The transistor only needs to handle the PS_ON, everything else would stay connected all the time. If the computer is off then it should not draw any current at all (or at least very little). The question is how long can it be left in this state before the trickle drains the battery?

digitallexus · 04-05-2003, 02:29 AM

ATX motherboards do not turn off and stop using power when the PS_ON goes high (i.e. is not being pulled low)

PS_ON is a signal input on the power supply side. The motherboard simply uses it.

The Power supply pulls the line high (+5v) by default. To turn on everything, the motherboard pulls the PS_ON line low and holds it there. This causes 12v to flow across the transistor and power the relay coil, in turn powering the various rails.

Telek · 04-05-2003, 02:36 AM

Ok, what about PowerGood then? If that goes low will the motherboard turn off?