carputer build/repurpose a lappy. no, tablet

[Psych0matt]

Long story short, I have a laptop that functions perfectly aside from having a battery that doesn't batter. To spare some details, I reinstalled a fresh XP copy, tweaked some things, and got centrafuse mostly running how I want (other than some plugins and codecs for video). I have about 12 seconds until complete hibernate from button push, and about 15 seconds from cold start out of hibernate until music starts.

 

My hurdles are switching it on and off. My plans are to get a DC-DC laptop adapter that's the proper voltage and whatnot (about $14 online), and then wire a cigarette lighter in somewhere so that it's easily disconnected. I haven't rewired anything yet since it's cold, but I'll probably run a thicker power wire to a distribution block, and then run my amp and this off of it.

 

So, with the power mostly planned, here's kind of the setup I'm going for:

 

If I hardwire it with a DC-DC plug, and then just have something "push" the button after a few seconds (after crank), that would do 100% of what I need it to. Basically this

 

turn key on

power comes on, utilizing remote wire in the same manner as an amp?

5-10 second delay to allow voltage spike from crank, crank and start

button press once started (doesn't have to involve the 500rpm thing, 5-10 seconds will do the same thing, just on a timer instead of an rpm signal)

 

 

the issue will be going into hibernate, having it retain power for maybe 30 seconds before cutting off

 

turn key off

maintain power, button push

30 second delay

cut all power

 

 

 

I'm open to thoughts and ideas. I know I can buy something to do all this, but why spend over $50 for something I should be able to do for less than $20? I may solder in a secondary power button lead off of the original, so that I can basically run a remote button somewhere if I need to for testing purposes.

 

 

My goal is to use this primarily as a carputer, but maintaining it's laptoppiness. for reference, it's a celeron 2.4ghz processor, with 700 some megs of ram, so plenty to run audio and some decent video

 

 

 

OH! I almost forgot! My plans to start are to run a cd HU in the foxglove, and maintain stock speaker setup, and just run this into the aux jack for now, so the only issue with this is finding the happy medium of two separate volume controls. And then of course I'll run a touchscreen in the stock HU location. I thought about putting it where the DIC is, but it's gonna be too difficult I think with the shifter

Edited January 31, 2014 by Psych0matt

[RobertISaar]

i still like the idea of using a maximum cheap arduino to intelligently control the on-off functions. that would have more than enough I/O capability to do what you're wanting and won't have any real downsides(other than possibly begging for someone to write a really quick program).

[Psych0matt]

Well, I have no idea how to use/do/accomplish what you said, but I like how you think!

 

I just feel like it can't be that hard to accomplish what I want, I just don't know enough about electronics to do it on my own.

[GnatGoSplat]

http://www.mp3car.com/power-supplies/155899-carputer-how-to-make-your-laptop-start-up-boot-automatically-video.html

He is using a PIC instead of AVR/Arduino, but it's a similar idea.

[Psych0matt]

Yep, have definitely seen that video! I've been watching/reading a lot of things, but that doesn't make up for my non understanding of in depth electronics This is getting me closer though

[RobertISaar]

something as simple as these:

 

https://www.sparkfun.com/products/12640

https://www.sparkfun.com/products/11575

 

would do well enough for what you need. you'll need some external stuff to them to control relays, but not difficult/uncommon/expensive components. that pro micro has 4 A/D pins that can be used to sense stuff like where the ignition is currently switched to and 12 other pins that can be used for input or output, like simulating a button press, holding a relay in the powered state, etc, etc.... for what you need, that would probably cover it quite well. the redboard is capable of doing a bit more, but whether you need the capabilities of it are in the air.

[Psych0matt]

well, I don't mind buying one (in a week or so) if you guys can walk me through it. I don't mind getting my hands dirty, and i've done a little bit of soldering, and know my way around a desktop, not quite as much a laptop but I've been in a few. I don't mind spending $5 more, that's not a big deal.

 

from what I gather, I'll have to power this seperately? once programmed, I'll have to run a few wires to it, such as?

 

I'm sorry, I'm a total newb at some of this stuff, but he can be taught!

[RobertISaar]

if i had to guess, i'd say you could probably power it through a USB cable permanently if you wanted. otherwise, you would need to supply a regulated 5V to the board or feed it something its onboard regulator will accept. says up to 12 volts, but you'll see ~14.5ish on a regular basis, so that may be too much for it. would need to regulate externally to keep it at a reasonable level, either directly down to 5 volts or let the external regulator drop it down into the 7-12V range and have the onboard regulator deal with it from there......

 

as you can see, there are a lot of possible solutions to every problem.

[Psych0matt]

 

• Input voltage - 7-15V

 

 

that wouldn't work? At any rate, this may be a good solution, but I'd need someone to perrgram it for me. Or at least tell me what to do, and how to wire it.

[RobertISaar]

that would be more than acceptable then... i must have been looking at the specs of the other one to come up with that number.

 

writing the program shouldn't be that difficult for anyone with any kind of exposure to code, though you'll probably need to download the arduino IDE as well to upload the program to it. it's done through the USB cable, relatively simple.

 

wiring it.... will take a little forethought to make sure not to go through too many revisions. rewriting code is a lot better than changing a board.

[Psych0matt]

Yeah, I don't have an issue with the wiring if you can help me figure out what needs to happen, and I know a bit about code, although was never good at it at all. I may pick one up next pay day if you're willing to do some coding and help me figure out wiring! I'd even compensate you very handsomely, perhaps with taco foods or something!

 

 

Looks like you can just run pins into the board?

The link posted earlier, i know it's different, but perhaps a good idea on what code to run?

[RobertISaar]

after reading all of the comments.... some have expressed concern about the power dissipated in the onboard regulator when using near 15 volts..... i also have a bit of concern about that. it may be within spec, but it is also really high.... i would instead feed 5V directly through the USB connector or use something like a 7809 regulator to drop the car's power supply down to 9 volts for the onboard regulator to drop down to 5V.... spreads the heat out a bit more and you can attach a heatsink to a TO-220 7809 pretty easily.

 

pins.... the pin blocks as they are generally get used by headers, while you could probably get away with..... 20 or 22 guage solid copper wire stuffed into them, but i wouldn't recommend it, there is a lot of chance for something to fall out. those are surface-mount headers as well, so would need to remove the headers, solder around them or solder stuff to a header, then plug the header in when finished. maybe some adhesive to make sure it doesn't come apart as well, that could solve the single wire issue too.

 

also

 

[Psych0matt]

after reading all of the comments.... some have expressed concern about the power dissipated in the onboard regulator when using near 15 volts..... i also have a bit of concern about that. it may be within spec, but it is also really high.... i would instead feed 5V directly through the USB connector or use something like a 7809 regulator to drop the car's power supply down to 9 volts for the onboard regulator to drop down to 5V.... spreads the heat out a bit more and you can attach a heatsink to a TO-220 7809 pretty easily.

 

pins.... the pin blocks as they are generally get used by headers, while you could probably get away with..... 20 or 22 guage solid copper wire stuffed into them, but i wouldn't recommend it, there is a lot of chance for something to fall out. those are surface-mount headers as well, so would need to remove the headers, solder around them or solder stuff to a header, then plug the header in when finished. maybe some adhesive to make sure it doesn't come apart as well, that could solve the single wire issue too.

 

 

 

 

 

Well, when I have fundage, I shall buy, and we shall converse, and we shall make a thingy!

[Psych0matt]

to run a usb power, what would be the best way? If I break off in the rear and wire it up with some sort of quick disconnect (cig ligher), I could split that into two, one for a usb which I have a few lying around, and one for the lappy?

[RobertISaar]

 

i have the IDE downloaded now, i'll see about punching out some initial code in the meantime. it shouldn't need to be very complex since it is essentially only needing to trigger a relay or two(or get fancy and replace relays with FETs), simulate a button and watch what the key is doing. watching for a running engine could be done a few different ways, like tracking the system voltage to make sure that the alternator has been producing voltage above what the battery could supply. or watching the fuel pump voltage to see that it is staying energized for more than the 2 seconds after cranking/key-on will cause. or some other fun methods.

 

for USB power.... i'll mspaint together something i have in mind.

[RobertISaar]

this is extremely simplified and doesn't show all of the connections, but i'll run through the basics quickly.

 

 

following the power souce starting at the battery, runs through the ignition and when run is encountered, it powers a relay(or FET) that supplies power to a USB power supply(or 5V regulator or ???), which then runs to the arduino and allows it to power up through the "some constant +12V power source". now, the arduino will also be able to control relay 1 through one of the outputs and will do so at all times once it boots up. this allows the arduino to continue operating after the ignition is no longer in the run position(so, cranking, bulb check, off).

 

the same(or another, doesn't matter for this demo)constant +12V can also be used to route power through another relay that the arduino controls on its own to turn the computer power supply on and off. it would also have the circuit for the button press simulation but i didn't bother drawing it in.

 

i imagine the remote on wire should be in there somewhere to allow you to turn everything off for when you don't want any of it on, but i also didn't draw it.

 

operation in the accessory position could also be done and perhaps bypass some requirements so that it will boot on sooner?

 

 

 

that is the gist of it and the basic explanation of how it would work. if there is something i haven't mentioned, i've probably forgotten about it and would be a good idea to bring up before the wire diagram that doesn't look like poo gets drawn up.

[virtuetovice]

Not to be that guy but couldn't you just run a hot-on-run wire to a momentary relay and wire the relay's output directly to the power button?

[RobertISaar]

Not to be that guy but couldn't you just run a hot-on-run wire to a momentary relay and wire the relay's output directly to the power button?

 

i will break you.

[RobertISaar]

 

actually, i seem to remember some kind of issues popping up that way, but i can't remember them.

[Psych0matt]

essentially what I'm reading/looking at is that key on = start up of arduino, turn on power source, push power button. key off = push power button, wait, shut down of power source?

 

That's the basics of what i need, yes. If accessory power is achievable easily, why not? I imagine you could use the signal for when the key is put into run position, before crank? If not, I'm not that worried about that, mostly the on when car starts, off when car is turned off, but using the button push for hibernate/unhibernate.

[Psych0matt]

the laptop is not in the picture, correct? thats the arduino board? I was kinda confused for a second. from there I would have to tap into the power button, or is that something that's done elsewhere?

[RobertISaar]

essentially what I'm reading/looking at is that key on = start up of arduino, turn on power source, push power button. key off = push power button, wait, shut down of power source?

That's the basics of what i need, yes. If accessory power is achievable easily, why not? I imagine you could use the signal for when the key is put into run position, before crank? If not, I'm not that worried about that, mostly the on when car starts, off when car is turned off, but using the button push for hibernate/unhibernate.

 

that is the very short version. after everything is done, the arduino will then shut off relay 1 and power itself down. perhaps use another A/D channel to watch for some indicator of the computer being completely shut down rather than a fixed-length time for everything to shut down? the amount of power the laptop would be drawing while hibernating would already be VERY small, but this would bring it down to 0. then the arduino down to 0. so, once everything is off, should be drawing no more power than what it does with a stock radio.

 

the laptop is not in the picture, correct? thats the arduino board? I was kinda confused for a second. from there I would have to tap into the power button, or is that something that's done elsewhere?

 

yeah, didn't draw it for lack of space and the extra complexity it would add for the pic. the power button should be a simple "connect to ground" to simulate it being pushed in.

[Psych0matt]

I like dis.

 

perhaps use another A/D channel to watch for some indicator of the computer being completely shut down rather than a fixed-length time for everything to shut down?

 

My only issue with this is on the off chance the computer doesn't shut down properly and hangs, then it would drain the battery. If it could generally run in that manner, but have a 5 minute fail safe (or something to that effect), that would be better.

[RobertISaar]

doable. i mean, the only thing the arduino would be doing during that period is sitting and waiting for things to finish. running a timer really wouldn't take any effort.

[GnatGoSplat]

Not to be that guy but couldn't you just run a hot-on-run wire to a momentary relay and wire the relay's output directly to the power button?

 

I don't know if momentary relays exist, but it's really easy to make one.

http://www.the12volt.com/relays/page5.asp#ctm

 

A few issues I can see is I believe the ignition cuts ACC power during crank, so turning ignition on would turn the laptop on, and after starting the engine, it would "press" the button again, turning it off. You'd also still have to devise a way to sense when power is cut and force the computer into hibernation.

 

I hate to be that guy too, but wouldn't everything be simpler and cleaner to sell the laptop and pick up something like this?

http://www.newegg.com/Product/Product.aspx?Item=N82E16813138393

Or maybe even a $40 Android stick. I bought one last year and never did anything with it. Been thinking it might make for a nice little carputer.

Although, I don't know what your vision is. If you're going for a clean, fully integrated carputer with touch controls, I'd definitely go Mini-ITX or Android stick. If you're looking for a setup like cops have with the laptop in the open and its screen and keyboard is how you interact with it, then sticking with the laptop makes sense.