It's called a shutdown controller and most of them are integrated into your PSU.
Newbie here. This is the only thing that's puzzling me before I start on the carputer project. I've searched the forum but not sure what I'm looking for to get the answer. How are you guys getting the carputer to wake when the key is turned to accessories on the ignition, and then sleep when the key switches it off?
Yep, the PSU controls it. For example, my M4 ATX power supply has a power, ground and ignition wire (like an amp, power/ground/remote). It has 3 switches you can change into different positions to tell it how long to wait after the ignition is turned on until it sends the startup signal to the on/off header on the motherboard, and how long it waits after the ignition is turned off to send the shutdown signal and then kill all power to the board so it doesn't kill your battery.
Example: if I have switch 1 pushed down (on), I turn on the ignition, it waits five seconds, then boots the PC, I turn the ignition off, it waits 5 seconds, the shuts down the PC and in 1 min kills all power to the board. I can put the switches in different positions to tell it to stay on all the time, wait up to 2 hours before shutting down, or act like a normal ATX power supply so when I kill the ignition it would be just like pulling the plug on your desktop.
Hope this helps.
If it hangs whilst shuting down/hibernating after a pre-set time (configured on the PSU usually via jumper settings) the PSU will cut power to the mobo.
Mine is set to ign off....wait 5 secs then send shutdown signal to mobo(and I have that set to hibernate within the power settings)....then 45sec later it will cut power completely to the mobo. So in this instance if my PC hung whilst hibernating after 45 sec it would jst be 'hard' shut down......, thankfully my PC hibernates within 20sec 99% of the time.
The DC-DC PSU sends the shutdown 'message' by plugging into the same position on the mobo that a normal on/off switch would.
Also, if all else fails I'm not sure about other power supplies, but I know that the M4 has a voltage monitor which constantly monitors battery voltage and if it drops below 11.2V while the car is off it will cut all power.
I don't mean to highjack this thread but since its pretty close question to whats he asking. Okay here is what I have, its an laptop with a broken screen but a good battery. I was wondering if I could somehow have my computer go to stand by when I turn off the car and then just use the battery on the computer to last it until I turned my car on and then have my computer come out of stand by. I have the power cord to turn on with the car and off with the car. I figured I could set my computer to go to stand by when on battery for 20 seconds or whatever I just dont know how to get it to come out of stand by.
Wow that was a quick reponse and excatly what I needed.