I am currently planning to install a carpc in my car and I noticed that there wasn't a cheap effective solution to shutdown/startup the computer while controlling the power supply as well. Now, this is not a powersupply unit, but rather a way to turn on/off the powersupply unit while also turning on/off the computer.
So, for the past month or so, I have been developing a homebrew solution that works well with laptops and desktops. I'm currently going to use this in a laptop, but it can also be configured to be used with a desktop. I want to make this product open source and available to public, because I want people to improve on this idea. This system is quite cheap, when compared to other products and easy to build. I haven't come with a total price on the cost, but I would estimate about 15-30 dollars, depending on where you buy these parts.
Before, I make this available, I would like to know if a lot of people are interested in this. If a lot of people are interested, then I will make a nice diy instructions on how to build this device. Please vote on the poll. Thanks.
It is interesting to see that there are so many solutions to this and that so many think it is a problem. And that so many (including myself) that takes the money and time to do something of their own.
Obviously the "smart" power supplies does not do the job.
And the PC sw add ons are cheap but have one major disadvantage. They only work when PC is on.
So what to do then? A small controller on a separate pcb with nice IO is the obvious choise. But I do not think you can do it in 15-30 dollars. that is more or less the pcb alone. Then you need connectors. power regulators etc... Mine is 100€ in parts alone in small numbers. (1-10)
Also I do not think it is worth while unless this pcb contains everything! It has to be the ultimate glue component for the LCD panel, camera, poweramp, buttons, LED backlightt.... And you want it to be fully configurable.
Before you start I also want to warn you about the amount of work ahead. I started 3 years ago, I've made 6 versions now, and I am starting to feel its doing what I want :-)
One problem I think with selling a unit like this is that it is very difficult in a simple way to explain what it does :-)
Try out my demo config app and see if it is not what you want. I share code too. Not to make people contribute, but to make people feel that they will not be left in the cold.
Not sure if I should post this here, or stick to "our" E46 Work Log
Since I'm most likely end up with some kind of maintanance charging of the main battery of the car, probably through DEFA. I'm "allowed" to have the computer running while the car is connected to DC without fear of running a flat battery.
This would be a nice feature for your power controller Bes.
With a feature like this, I could RDP into my CarPC from my main computer inside. And when it's freezing -30 outside.... Nice and warm +25, with a large keyboard and screen, is way much better than sitting out in the cold car, transfering MP3s or what ever
Would need some logic on the input DC connector to check for current or something? Perhaps a simple relay and it's all good?
6 versions already? LOL It never ends does it?
I'm on my 4th revision now using an "intelligent" DC-DC as a slave and using every I/O pin the PIC has. But it's all custom. It's very easy to get out of that general purpose area where nobody else would need the extras.
Yeah, it's a lot more than $30 in parts and it's not what anyone else would use. The 18F2455 for example is $5, oh and uses 50mA alone when the USB is active, 20mA without, so it has to sleep and use ints as much as possible. Relays are expensive, use MOSFETs.
Then just try to look at those extra 16 or so I/O pins and not use them.
Hmm, maybe you guys are right. I'll try to make a cost writeup and find the exact total cost.
You should really have a talk with Grey, Crinos.
He's got a small linux board that is on permanently for tracking etc. And he has offered to send me an image of the system if I was interested, so I am sure he will help you out. Using that board he can send command to my board to turn the PC on (and off). The PC is in fact connected to my pcb via virtual port on the Linux board.
I really think that could be worth a thread of its own!
Hmm, thats interesting but I have already developed this system. Although, I have not tested inside the car, I have used a power supply to test this system and everything does work. It is continuously checking to see if the acc/igniton line is off or +12v. When, it sees that the car is on, it will trigger a relay to turn on the power line coming from the battery, so all devices i.e. monitor, pc, usb hub, etc are powered, then it starts the computer and continues to monitor the ignition line. When, it sees that the car is off, then it waits about 10 seconds, and then starts its shutdown sequence and after about a minute it cuts off the power going to all devices. I'm using this for my laptop, so I have the power switch wired and the lid switch wired. But, it can also work on the desktop, because you can use power switch on the motherboard for startup/shutdown sequence.
Well, another problem with making it cheap, at least using a PIC is that it will cost each person for the programmer, and not everyone wants to learn how to use it. I'm not trying to knock your work.
For a laptop, you could increase the off-delay to make sure the battery charges too. Those don't take as much power but it's good to keep them charged fully.