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Ask Slashdot: How do you build a PC for the car?
Bruce Linley sent in this rather
interesting question: "Whether
it's an MP3 player or a GPS navigation
system, what hardware is best suited for
use in an automobile based PC? Hard drives
must be tolerant of excessive vibration;
the CPU must operate locked in a trunk
where temperatures can reach 100C or -50C
and where there is poor ventilation. The 12V
power in the car may be somewhat dirty and
variable. I/O cables may be subject to
noise in long runs...and so on. Help me pick
the components for the most rugged and
reliable automotive PC!" Man! I would
love to do something like this also!
Comments, folks?
I remmeber a guy installing a tv in his RX-7 for video console/pc... but he ran windows 95... anyhoo... i think the car "crashed".. hence no webpage =)
Netwinder
Check out this link:
http://utter.chaos.org.uk/~altman/mp3mobile/
This guy built a Linux-box for his car to play mp3's. Lots of technical info, including details on the powersupply (Tricky indeed)
Menno
I would go with a PC104 machine (space and cooling requirements; realize you probably won't find that PII (or even that K6-2) available for it.
If that fails, I would try industrial and singleboard computers.
Take a look at components recommended for homebrew wearables -- wearables do get beat on a lot.
Also, never ever discount the idea of insulation and heaters. It might be better to put money into normal components and the stuff to go around them than to buy expensive all-temperature hardware.
http://www.mp3car.com/
Where are you driving that your trunk temperatures would get as high as 100 C? That's the boiling point for water!
Put the hardware under the dash, or somewhere else inside the passenger cabin. If the occupants can handle the temperature, then so can the machine.
- 1MB Flash ROM
- 8MB DRAM
- LCD controller
- RS232 Serial port
- I2C Serial port
- 10MBit Ethernet port
- A bunch of other IO Lines.
Currently they are still laying out the board, they say it will cost less than $150 when finished. To use it in a car, you would need to attach a power supply (3.3v for the board), LCD or some other kind of I/O, and, if you wanted MP3, an MP3 chip. (i.e, you would build your own board with an MP3 chip and power supply that the SIMM plugs into.)Linux has already been ported (this system is similar to the palm pilot, you can download source code or a binary image to run in the Palm Pilot emulator).
go to www.empeg.com
It's an IN DASH mp3 player that runs linux!!!!!
Modify this puppy to do what you want and for alot less
than what you would pay to do it yourself.
Otherwise look at www.ampro.com and check with the wearable computing crowd. they've been doing this for years.
I just noticed
http://www.crystalvisions.com/a-class.htm
which says it is suitable for mounting under
a dashbord and which has DC input.
Laptop hard drives are very robust. if you shock mount the thing it will be fine
:-)))))
DONT use a solid state drive unless you are extremely rich.
Go laptop hard drive in a cannablized auotmotive
cd player mount (the inside guts) and you can play basket ball with the thing
THINK PEOPLE!!!!!! why buy when you can make a
real solution with your mind!!!!
Besides, I'd just use the www.empeg.com unit. all the hard work is already done and they will give you access to the GUTS!
and it runs LINUX too
They're rugged "laptop" computers used by the Army, and they can take a lickin'.
This has already been done. Check out the AutoPC, you can buy it at select retailers. It plays MP3s with additional software and comes with a CD player to boot.
http://www.microsoft.com/windowsce
cyrix 133's (the PR 166+ kind) run winamp just fine, with stuff like photoshop open at the same time. so if it works under win95 it damn well better work under linux.
only hitch with a cyrix in that kind of environment is that they overheat pretty easy.
ghall@justice.loyola.edu
It really depends on how much effort you're willing to put in. If you're willing to write some drivers, and potentially port either the Linux or NetBSD kernel, I'd go with something like a:
- StrongARM SA1100DA CPU (these things are sweet; they're fast, and pack controllers for EVERYTHING on board).
- 16mb RAM
- 16mb Flash memory
- CD-ROM to store MP3s, maps, etc.
- Possibly, a TI DSP for FPU-intensive tasks (if you do a web search, some guy did his thesis on optimizing MP3 players on DSPs; he can give you the code to get this working)
Compaq's CRL, and a few other places, make decent StrongARM-based boards. It'll take a lot of hacking to get working with the rest of the hardware, though. Only a few run Linux or NetBSD without modifing the kernel. The StrongARM also has no FPU. It's still an incredibly sweet chip (fast, robust, generates virtually no heat). If you want a quick solution, go with a PC104 with a decent speed Pentium.
Hard drives are too unreliable for long-term operation in a car (don't believe people who give you BS about how great notebook hard drives are; in your conditions, they'll fail after at best a few months). CD isn't great, but it'll almost certainly work better.
- pm
You could put a second alternator on and run a second electrical system. Have that go to a high output power inverter. And that to a nice ups. Seal the trunk throw an ac unit in there mount the computer case (or put a temp sensor and some fans and new ducting to vent the trunk(which you can power by putting a solar panel in the back window)). Pack the harddrives in that jelly stuff (sticky hand thingies that you get in quarter machines). Get an active matrix display and mount it so it can retract under the seat and you are good to go. Or at least that was the idea i came up with. I really wanted to do that to my car but as I have no money I couldnt see if it would work. Oh, yeah I think you would need a brighter backlight for the display so the sun wont wash it out.
Silly Freak
dtfm42@hotmail.com
Can a CD-ROM work ok in a moving car? mp3's only need at most 16k/sec for almost all of them. Can say a 32x(4800k/sec max) handle this on top of skipping? how long can it last in such an environment though? Maybe it will work if you set the buffer way up on the mp3 player(which linux mp3 players have an adjustable buffer?). I'd like to here from someone who has tried this. I have been thinking about this for a while I'm not sure how I'd approach it. I would like to build an expandable(support for plugins based on an open standard), open source car computer by this summer or so. Input/output would be done through a simple custom head unit in the front. Parallel or an I/O card(based on Intel 8255) would handle the data. The program would basically be an advanced menu system for the LCD display in the head unit, which organizes and makes the plugins easily accessible. The plugins could include anything. They could even drive external hardware or control other devices through the I/O card. Or maybe just ping the server upstairs to make sure you don't drive out of the garage with the hub and half of your bedroom wall. =). A larger text LCD display unit(Like the big one from Matrix Orbital, but not in the that funky green, probably amber or a powder blue) would probably be used. Monitors and color LCD panels alter the character of the car in a way I don't like. I am aiming for something small, robust, powerful, and subtle. It should do it's job and shouldn't dominate the driving experience or atmosphere of the car. One thing I am not sure how I'd approach is the architecture of the plugin system, with respect to coding at least. If anyone has any suggestions on design, codewise or aesthetically, I'm open to anything. Right now it seems like it'll start on a p90 in the trunk, 32MB RAM and 2.1 gigs. Also, this is a bit off topic, but can Linux use a Sound Blaster PCI 128? It's what I have here and I don't see anything about it in the hardware HOWTO.
EMIce
emice@earthling.net
Perhaps I can be of assistance on this one. I have a sub-notebook system mounted in my aircraft. One of the serial ports on my system connects to a trimble GPS system, the other serial port connects to a panel mounted fuel flow meter. I was fortunate to find a flow meter with a serial output - 2 pins only, data and ground at 1200 baud odd parity! I use the linux gpsd deamon coupled with mayko's mxmap to produce a moving map display. Consequently I get flight track, flight position, time to fuel exhaustion, fuel remaining at destination, pounds of fuel used per mile, etc.
I elected to use a sub-notebook instead of a panel mounted SBC because I routinely have to update dozens of very large maps i.e. 10MB compressed tiff images. It's amazing how many new of cell towers poping up, an up todate map is essential. The portabilty of the sub-notebook allows me the option to use NFS to upload the maps needed for the flight at hand from my home server. I'm currently using a Toshiba Libretto 50. It's tiny, the size of of a VHS cassette, has 32MB of RAM, and 4.3 MB of disk and weighs aprox 850 grams. Although it's compact, it's not particularly rugged.
If you want something really tough, I'd recommend a grid computer. A grid can survive a 6 foot fall onto concrete and keep on running.
My company once had a grid that accidently fell 400 feet from a helicopter. The metal case was dented all to hell. We figured we'd do more damage by turning the thing on so we took it to the repair center. The tech at the repair center, looked at the case, turned it on and asked us what was the matter with it. As it turns out our only expense was the cost of a new case.
If you're looking for dedicated single purpose computers that are cheap and reliable I can recommend Parallax Stamp, Vesta SBC2000-62 and Wilke TNN-R/1. These systems cost between $29 and $59. They are all about the size of a silver dollar. These system have between 16 and 36 digital lines. All of them are programmed using a simple but powerful compiled basic.
B. Collins
shark@apk.net
I play MP3's all the time on a Pentium 100 with the added load of NT Server, a mail server, and loads of other stuff running and rarely exceed 25% CPU utilization. FPU seems to be used more intensively to encode the MP3, not to decode.
I've also played MP3's on Cyrix 233MHz chips no problem whatsoever, with Netscrape, X Windows, KDE, and all kinds of other stuff running (on Linux)
You are on the right track for doing this. I've designed, built and installed some remote PC/Datacomm equipment for some wild places.
I've got a series of radio modems with little single board computers and linux (stripped down slackware) in flash drives. A bit expensive. They provide a handfull of ISPs with a cross border data stream, and cisco routers running BGP at the ends. Very remote countryside, power is where we, ummmmm, found it. I've also done a couple of PC email/wefax systems on board of yachts and one oil platform.
So to start with, your biggest problem is power conditioning. Rule of thumb is that it should be 50% of your total cost. That means spend as much on your power as all the rest of it. Then you will get much better reliability. Is the system going to run 24/7? Then add a second alternator/generator to your engine, and create a completely separate power supply. You will find it easier in the long run, and when you sell the car later, it will be easy to remove the system and transfer it to your new one.
Follow the advice repeated repeatedly above and use a flash card or module in place of a hard disk. Use lots of RAM to prevent any swapping (dont create a swap partition on your flash drive or it will die within a week). Moving parts are *BAD*!!!
Vibration, dust, dirt, moisture, heat and ventilation are the next concerns. The solution is not easy, but keeping it dry and clean is the priority, cool is next.
After that, physical security. All the expensive bits should be in a locked box or wheel well. It should house the battery for the security system, and be difficult for thieves to break into.
And you probably dont need a 600Mhz pentium, it will just heat up your car needlessly. Look for low power 75/90 Mhz parts. Its enough for linux!
Get this working, learn all the various technologies, and you will have a bright future as a consultant. Good luck.
You are fine with a disk. A good laptop drive should withstand a 100g shock when operating. You, however, wont.
Some government agencies have really nice set ups in sport utility trucks (ie: ford explorers) ... Everything is mounted in the rear, and they have touch screens mounted in the front...very nice setup. Unfortunately I can't tell you the specifics on the hardware.
forgot my password again ..ohwell..anyways i ..we design our own housing..and use toshiba laptop hdds(4x4GB worth) single board computers etc..
..
work for a startup oem that designs rugged built systems (air tight, fire resistant etc) for surveilence in transit situations..trains cars, busses, etc
www.tsswitness.com isour (lame) website
aphro@aphroland.org
put a switch on your computer and start the 'puter AFTER having started the car.
Canadian AC
Run the cigareete lighter DC through a 12V gel cell battery like the kind that comes with bag phones. This will compensate for some of the voltage fluctuations and crises.
Steve Roberts built the BEHEMOTH bike which did have several computer (Mac, Sparc). He used hard-drives and other storage media. His web site is www.microship.com. Microship happens to be the name of his new project; a boat in the same idea as BEHEMOTH.
Check out www.empeg.com for the best. I'd have to go with alot of people and say laptop-style hardware is the way to go. For the hard drive, I might even consider using something removable like an external syquest drive (has anyone thought of this?) due to it's durability and portability. It'd be a cinch swapping out songs and the like.
With a UPS or something else to clean up the power a little, you could have a sweet auto-mp3 box. Just mount it in back like your CD changer.
Me and a friend are starting a project for his car.
http://www.zerosanity.com/musicmonster//a
-elixir
A throttle body is not variable voltage, it is single voltage that switches on and off rapidly depending on engine speed. At full throttle, the injector is on all the time. The O2 sensor measures the Air:Fuel ratio trying for that perfect 15:1, and the computer bases the switching of the injector upon the O2's output. The computer usually uses the temperature sensor to control idle speed so that it runs at a higher idle speed when you first start the car until it is warmed up. I've been wanting to do something like this to my car for a while.... If nothing else, just for tuning purposes...
mneag@ka.net
Try panisonics armored note book. We have one at work. It meets and exceeds the spects you gave
Try this
If you're going to stick the thing in a cooler anyway, go with an electic cooler. Coleman and some other company (Igloo?) make these, and they're designed to run off of automotive voltage anyway. They'll drop the temperature by about 40F from ambient.
Just be sure you get the polarity right or it turns into an oven, instead! (Hmm, you just might want to do that in winter.)
Yes. Both Linux and NetBSD have StrongARM ports. However, if one either buys or builds a StrongARM-based board, one still has to port it to that particular board. System architecture is a bit more than just CPU; notice the number of PPC Macs that Linux/PPC didn't run on when it was first released. Last I checked, the Linux/SGI port only ran on Indys (although that was a while ago), and not other machines, even if they had the same CPUs.
It is possible to find boards that run either (Corel Netwinder and Compaq Itsy run Linux, Compaq Skiff runs NetBSD), but I don't know of any boards that meet the poster's specs that have ports of either.
I'd also like to add to the list:
- Either Matrox Orbital panel for text-only output, or a cheap LCD panel that interfaces to the SA-1100's LCD controller. The latter will be a bit more of a pain to do.
- Either a twiddler for alphanumeric input, or buttons hooked up to the StrongARM's GPIO pins for simple input.
Yes. Both Linux and NetBSD have StrongARM ports. However, if one either buys or builds a StrongARM-based board, one still has to port it to that particular board. System architecture is a bit more than just CPU; notice the number of PPC Macs that Linux/PPC didn't run on when it was first released. Last I checked, the Linux/SGI port only ran on Indys (although that was a while ago), and not other machines, even if they had the same CPUs.
It is possible to find boards that run either (Corel Netwinder and Compaq Itsy run Linux, Compaq Skiff runs NetBSD), but I don't know of any boards that meet the poster's specs that have ports of either.
I'd also like to add to the list:
- Either Matrox Orbital panel for text-only output, or a cheap LCD panel that interfaces to the SA-1100's LCD controller. The latter will be a bit more of a pain to do.
- Either a twiddler for alphanumeric input, or buttons hooked up to the StrongARM's GPIO pins for simple input.
- pm
It even runs linux!
Don't remember the url but if you search hitachi's web site, they claim the processor has a linux port.
Pyro
A better question than "What can it take?" is "If I want one, where can I find one?" This is not a canteen or backpack or spent bazooka tube we're talking about here.
Jumptec sells nice K5-133 Pc104 systems for a reasonable price (pentiums available as well), and 486 DimmPC's (used on the "smallest webserver"). Obviously the DimmPC will be smaller. Id suggest going with a 48 meg flashdisk and/or a 48 meg ChipDisk, which is basicly an IDE flashdisk which is compatable with standard EIDE harddrives. Id also suggest getting an LCD display, or a small tv screen. Also, you might want to get a pcmcia cdrom and controller.
I used to work for a company that had some ancient 386 laptops, with okay LCD screens. Would it be possible to yank the LCD display out of a laptop, and mount it in the dash? Can one convert an LCD display to run off of a regular video card?
Does anyone know how to make/where you can buy a power supply that produces all the necessary voltages? (12v, 5v, -12v...). going from 12dvc -> 120vac and back down again is a waste.
Been there done that 4 years ago. Used a Intel
87c51GB. Displayed Temps, FI Pulsewidth, Dwell,
Spark timing and others on a 87 Firebird.
The 133 is $2499.
Cars run much better without computers! Just get something with a decent engine, and listen to the noise. You want to escape from the damn things somehow ;-)
afrosquad.com(true eleetees) made use of their plethora of technical ability and invented the mp-chevy, a delictable addition to any hick truck. check it out. bow to snowman as your official froness leader. later.
That way I can weedle my brother-in-law into making one for me...
>The specs for automotive electronics include:
> 1. Withstand 2x battery voltage (24V)
> 2. Withstand reverse battery voltage
> 3. Operate at 1/2 battery voltage (cold and/
> or cranking - might not need this)
Not at all hard to achieve, add in a PC104 board use PCMCIA flash disks, way cheaper that the Disc on a Chip and higher capacity to boot. For a display just use one of those LCD 40x2 displays.
FedEx has had (for QUITE some time) mobile computing in their delivery vehicles. They run a weird sort of application that once errored out enough that the driver asked me to take a look at it (I was a security guard on a loading dock as a student.) knowing that computers were my thing. The sucker runs DOS, and a monochrome screen. I don't know any more about the hardware save that it uses X.25 over the CB radio to keep in contact with the 'home base' or whatever they call it.
I believe it's actually 14.7:1.
Why doesn't someone look at what is commercially available for car MP3 players. Check the hardware page at mp3.com (http://www.mp3.com/hardware) they have a list of car mp3 players being offered or currently offered. Just about everyone uses a hard drive, therefore one can assume that a HD is suitable.
"Never Argue with a Moron" Gray
There's some more embedded computing resources in Embedded Computing page of Gary's Encyclopedia.
Actually, the police run into this very problem. When installing lots of goodies, such as radar guns, GPS systems, and video cameras, these all require a clean source of power, as they all (plus the radio) use RF. The solution is to connect another car battery to the generator. The battery serves to clean the power. Also, if you want to preserve signal integrity, consider using shielded cable (like RCA or coax), and grouding the shielding. This ground must be completely separate from the new power system, or else you're right back where you started.
What sort of price range are we talking here?
:^)
Please email a response to
Shane Simmons
(Not anonymous, not a coward, just lazy
The NetWinder runs off of 12 (or 9) VDC,
has built-in stereo audio and even NTSC
video in/out (DM version only).
I'm thinking of trying one in my plane
for in-flight entertainment (and to
interact with the GPS receiver and engine
analyzer).
Now if it could just play DVDs...
100 f not 100 C
Use big filtering capaciters to smooth out brownouts and Surges, Although if you got a 24 volt alternator you can power a power supply VERY easily to get +12 and -12.
Use an inverter and then just plug in the regular computer power supply. The inverter will produce clean AC voltage/current and the normal computer ps will provide the clean 12vdc and 5vdc needed.
Wire in a digital thermostat into the cooler and have the computer monitor it. It could then turn the cooler on and off. In fact, you could hook in a relay to switch the polarity on the unit so the computer could heat or cool as needed. Damn this is cool stuff.
Perhaps I'm missing some things which perhaps should be obvious, but I do not understand the practicality of some of the things that people are suggesting. Why would anyone need a largish (6") color LCD display for anything but GPS? Playing Quake while in queue at the Taco Bell drive-through doesn't quite seem worth the expense, or (moreso) the installation difficulty. Flashy visuals from an MP3 player might be a good way to supplement a driver's boring personality while the passenger plays with the display, but how much are you willing to hack up your car for a glorified toy? A small, RS-232-driven character-based LCD display will serve just fine for listing song names and configuration data.
That said, I'm also extremely wary of hard drives in cars. Some handle shock well; most don't.
I accidentally dropped a 2.5gig Seagate Medalist, rated at 75g non-operating shock, onto a soft mattress from a distance of approximately 3 feet. It did not survive. Seagate replaced it under warranty, but (of course) all data was lost. Do you really want to have to worry about making backups of your car?
Additionally, hard disk heads quite literally fly above/below the platters using the same Bernouli effect that keeps aircraft in the sky in conjunction with the air movement sparked by the rapidly-spinning (5,400-10,000RPM) platters. However, unlike an airplane which typically never gets below a few hundred feet from the ground except during takeoffs and landings, these heads are flying *very* close to the disks beneath them. If they contact the platters, Bad Things *will* happen. Chances are that the hard drive will be damaged before you even have a chance to say to yourself "gee, those railroad tracks were worse than they looked." Granted, some drives handle shock better than others and, indeed, some may be capable of withstanding shock that would crush your own body.
But why risk data loss and hardware failure, when hard drives are also unneccesary for the vast majority of what people seem to want to do with in-car computers? You needn't have a hard drive to boot the thing, use the thing, or modify the thing. You don't need the speed of a hard drive. You don't need the writability of a hard drive. You don't even need flash memory, unless you have some deep egotistical desire to have your in-car computer running before the engine's idle speed smooths out.
Instead, I propose an inexpensive, durable solution to booting in-car computers, which most of you already own: a floppy drive. Simple, compact, efficient, shock-resistant and foolproof. A minimalist kernel with sound support and a small filesystem with mpg123, or amp, or whatever, will fit readily onto a single disk. It is an unreliable medium, but it's also almost trivial to have AOL, Compuserve, and Prodigy send you a few extra boot disks to keep in the passenger compartment in case the one in the drive should fail.
For storage, use CD-R's. Yes, it's expensive to buy a burner, but still cheaper than a few gigabytes worth of Hitachi 2.5" hard drives. Further, the reader need not even be remotely fast; 1x will do fine for MP3 use, and will likely suffer *fewer* read errors than more modern 20-32x drives (the stupider ones of which will shudder violently enough with off-balanaced CDs that they will refuse to read them, while slower drives work consistantly well with the same disk).
Panasonic 1x CD-ROM drives can be found for less than $10 with some digging (and another $10 for a used Soundblaster Pro to plug them into) and up to four can be daisy-chained on the same cable. NEC 4x4 ATAPI slot-load changers can be had for $30-40, and the average Pentium motherboard will be able to support four of them. The Panasonic drives will work fine without serious hacks, the NEC drives will require a bit of creativity to get them to change disks (the program "eject" can do this for you) but offer random access to as many as 16 CDs.
Yes, I understand the feeling that *every* bit of music you have should be accessible immediately, at the push of a button. But with four CD-ROM drives, each with a disk loaded with MP3's at, say, 256kbps, you've got the same amount of music randomly available as people with 24-disc Redbook changers. If you encode at the more widely-accepted rate of 128kbps, you've got 48 audio CDs worth of music. All heat-resistant, sealed behind laquer, gold, and polycarbonate; all playable without contact (or near-contact) to the physical medium; near-zero chance of data loss, even in 100 degrees C car trunks. No, you won't be able to store data on your computer while driving down the highway, but why would you want to? And, as long as you're happy with the interface of your music player, you can use El Torrito to make bootable CD-R's and eliminate the problems associated with floppy drives, and the cost of flash memory.
Also, anyone making an argument for hard drives in cars by saying that CD-ROM drives do not function well when cold should perhaps rethink what they're saying. First, CD-ROM drives are not unique in this respect; audio CD players have the same problems at low temperatures. Second, hard drives and CD-ROMs alike use a spindle motor containing bearings. The lower limit of the temperature operating range is, in all likelihood, governed by these bearings and their lubrication. A hard disk may have a higher-torque motor, allowing it to reach operating speed in below-freezing conditions while a CD-ROM may not. However, just as engines wear more while cold when the oil isn't quite doing its job yet than when at operating temperature, hard drives will suffer increased wear at low temperatures, as will CD-ROM drives. Point is, you shouldn't *ever* run this sort of device at extreme temperatures, just as you shouldn't take a car out on the race track with an extremely cold engine. That a hard drive will allow you to abuse it in this way while a CD-ROM drive will not is largely irrelevant.
I've heard all the talk of different computing platforms being used in cars, and I have to say that, if you can afford it, picking up a p133 laptop is the way to go. They're rugged, and you can fit them under the driver's side seat. Plug a cigarette lighter-adapter and a tape-adapter in, and you're all set! The sound quality is decent, and if you run winamp at startup (win98) or write a simple python script to control input (other), you just need to pop the top and hit a key to advance/stop whatever.
Even better, some laptops will write their memory to disk, so that your mp3s start where they left off....
A lot of people here are saying how easy this all is. I thought exactly the same way, until I actually did it. I've just finished a PC in a car project (for MP3s), and there were numerous problems. Here's a quick list of the showstopping bugs, and what I did to get around them.
/dev, your /sbin/init replacement (write it yourself), and a few things in /boot (like the kernel). The system I've made boots and plays MP3s in approximately 5 seconds. One hint: keep the filesystem mounted RO and then you can kill the power at any time.
:-) without concern. Don't give bad advice! It's far worse than no advice at all. And certainly don't try and advise people about things you've never actually done yourself!
People who seem to think powering the PC is easy, are in for a rude shock. Regulators are far too inefficient. Naive attempts, like parallel 7805's in TO-3 cases, will never be any better than 35% efficient. A typical computer, with soundcard and hard disk (no monitor or netcard), will consume 50W by itself, and much of that is the CPU (I had a P100). This means the naive 7805 regulator is going to need to dissipate more than 100W! It got very hot, very quick. It's an unusable solution.
The proper solution is not DC-DC, but to go DC-AC and back to DC. The best solution here is to use a switched mode power supply. Building your own is far from trivial, and you'll likely have to wind a custom transformer for it. Don't even bother. You can purchase prebuilt DC-AC-DC PC supplies (with a standard P8/P9 connector set) for about $150US. I found it a lot cheaper to purchase a 12VDC->240VAC inverter at $50US and use a $10US PC power supply to convert back to DC. This also has the advantage of isolation, simplicity, and it was 80% efficient.
The second problem was heat. The car gets hot, and the hard drives do *not* survive. Adding fans does not help, of course, because the fans just blow hot air about. The solution was simplicity itself. Stick it in the boot. The cover provided in the boot was enough to keep it cooler for a bit longer than the car interior, long enough that the drives now survive quite nicely.
The third solution was pumping audio into the cars speakers. I sadly developed a ground loop! One I couldn't get rid of using a standard line isolator circuit. Once again, the solution is simple. A FM transmitter (stereo, of course) costs about $20 at any good electronics store and introduces no more than 3% harmonic distortion and noise. This avoids all ground loops, and isn't nearly as bad as some of the naysayers seem to suggest. It sounds better than most FM radio stations, at any rate!
The interface is fairly boring, because it didn't present any problems. Just buttons and LCD units, all plugged into the parallel port and games port. The games port provides for four buttons and you can get more buttons from the parallel ports "out of paper" line. The matrox-orbital units are nice but I've found comparable units (16x2 backlit LCD with mounting kit) for $15US! A fair cry better than the price wanted by the "fancy" kits. Be sure to shop around, and *ask* your local electronics supplier for contact details of suppliers for the more exotic items. A few phone calls can turn up a lot of good kit.
The software was also straightforward: build your own custom Linux distro. You only need
My only gripe here is that a lot of people giving advice seem to have not done any of this. They're saying things like "oh just use a 12V -> 5V regulator, like a 7805" or worrying themselves sick about the potential damage due to vibration. In practice vibration was a non-issue. The drives are robust enough to handle standard city bumps (carpark speed humps, the occasional gutter
This isn't going to work. At best, a heatsinked 7805 can sustain about 800mA. I've found the average Pentium, motherboard, soundcard and medium sized hard disk will need about 7-8A at 5V and 1A on the 12V rail. So your +5 and +12 rails are next to useless. The -5 and -12 rails are ok, though a little over engineered. You can get single IC solutions that do the voltage pump and oscillator all in one neat package, and presumably for less than buying all those discrete components.
You can boost the current a little by using a pass transistor, but the voltage drop from 14.4V to 5V over a pass transistor will mean you need to dissipate about 70W in the pass transistor. Using parallel transistors doesn't help either: it spreads the heat about, but you're still wasting 70W in your pass transistors. And now you have all the problems associated with thermal runaway (if you don't know what this is, it's a scary thing that causes catastrophic domino-effect damage).
Your best bet is to throw this schematic away and design a switched mode power supply. And when you've got a working design for a 12VDC into PC power rails, that you've proven works, PLEASE be sure to post that schematic, because I'm unable to design such a beast that works out cheaper than a simple 12VDC inverter into 240VAC and then into a standard PC PSU. That's economy of scale for you!
The parvus corporation has PC/104 enclosures that are meant to fit under a car seat with up to 8 PC/104 modules (which is a lot, if you aren't familiar with PC/104). I seem to remember that they were initially developed for a taxi cab fleet.
PC/104 systems are a little bit more spendy than most embedded systems, but it I'd go for a PC/104 system because of the expandability.
-tgm
a normal PC CDROM will not work in anything other than a super stable home environment. using a standard CDROM in a car will cause headaches. jusat load the data to a Laptop HDD and call it done. using a CDROM that is NOT designed for mobile use will just drive you nuts.
remember... NO CDROM except for loading.
About 15 years ago, we fitted 5GB hard disks to HP A600's in labs on (high-vibration) oil rigs. Experience confirmed common sense - mount the disk perpendicular to the axis of motion.
In a car this would translate to having the disk on-edge, and inline with the length of the car. That way impact forces of road shock, hard braking, and front/rear collision might cause read errors but not head-to-platter contact.
My opinions, worth exactly what you paid for them.
read this... this is the grad vision of detroit...
http://www.delphiauto.com/delco/delcocat.html
To buy old military gear, goto www.drms.dla.mil/publicsales.html, or call the base operator of a local military base and ask for the DRMO section/division/department.
D= Defense
R= Reclaimation
M= Management
O= Office
What input output devices is there to hook your computer up to you car computer(ecm) or does anyone know of a input output device that would measure voltage,restisance,ect.....so you you could measure o2 sens.,boost,techometer,ect..
You can email me at oobtttoo@aol.com. no spam!
I use an old 386 "noname" laptop I scored for $100 about 3 years ago. I run DOS and New Deal Office on it. (With only a 40 MB HD, I don't think it'd handle Linux and a Linux WP program.) It's never been a problem. One day I might get a newer "car computer," but it'll just be another laptop. Why take up trunk space?
--Robin Miller
You just need to find a company that sells robust CD-ROM drives. Car audio CD changers work perfectly fine with vibrations, hot, and cold, so I don't see why CD-ROM drives shouldn't work similarly.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
Yes, but an mp3 player can actually work with LESS throughput than an audio cd player, since the music is compressed. A single-speed CD-ROM drive would do fine.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
It looks as if they might not be carrying this model any more, though - the only Peltier units I see on their Web site are for older Socket 7 Pentiums, not Pentium IIs. (The model I have is a PAP2X3B.)
I've heard that Peltier units can get cold enough to actually freeze water, which is a problem. If the system is running in too hot an environment, it may cause condensation, which is definitely not a good thing.
Posted by Phantom of the Operating System:
just get a reliable CD Rom (or an array of them) in addition to the flash. Just put a limited amount of data in the flash, such as position, fuel calcs and stuff if you are going to use that as well, and boot the kernel from the HD (make sure you can boot from that sucker)
Flash is probably your best bet
Posted by Stephen "The Carp" Carpenter:
Who says the CPU has to do it?
WHy not make a hardware MP3 player on the
parallel port (netwinder has one I hope) and
then use the computer just to serve up the data.
Posted by Professor Krakho:
I actually work for a company that is starting to develop a "rugged PC" for automobiles. Check it out if you are interested at http://www.fleetpc.com
Posted by Imru al-Qays:
You'll want to look into the slightly unwise world of unofficial engine computer mods (mostly people tuning up the engines in their Miatas and Z3s, but who knows, maybe a pickup would work). Which raises an interesting question - if you had a machine running in your trunk, could you link it into the machine running under your hood (so to speak)? I myself would rather make a wearable that I could run off a dynamo on my bike, but the power supply is a little less consistent... TB.
Posted by JKX_1:
I'm using a 486-DX2-100MH w/ Win 95 and only 24 megs doing fine.
Posted by Davo-CC:
This may be an expensive option but I seem to recall there being a type of refrigerative storage container that runs on comparatively low power which also contains extensive insulation and a fairly small open core. This device is used to store medical supplies in remote areas, it is powered by a solar cell but I couldn't tell you much more about it than that (having only seen one on television a couple of years ago).
This would mean that you mount your PC inside the core of the box, and keep the unit on low power - perhaps a Libretto or similar device would be good for this purpose (they're fairly quick, very small, etc.).
You could power the cooling mechanism from a small solar cell array, that could perhaps be mounted under the rear window or even on the boot of the car; this is how the device was designed to work.
Another possible solution would be to use a small eski such as one of those Coleman coolers (for foodstuffs) and keep it inside that; something with insulation. I'm aware of cigarette-lighter powered versions of this with a small refrigerator built, it may be a bit over the top but it may provide a cooling solution for you.
They also let you put in foam padding of various grades to allow some form of shock protection inside the box, create the foam pads correctly with varying grades of foam heaviness and presto, a cooled protected PC. As for screen - that may be a different matter. I wonder how well those car-based LCD screens take the heat, my experience with overly heated LCD screens has never been good.
Hope this helps!
DT
Have a look at http://efi332.eng.ohio-state.edu/ for details of a Do-It-Yourself Electronic Fuel Injection system. Not exactly a PC in your car but it could be usefull if your looking for a partially sorted car computer... I'm personally going to be building an EFI system but you could use it for more general things.
PCs in general suck for cars and embedded systems... too heavy, too much power, too fragile. Things based on Motorola chips are good... Hitachi SH1 is another good, powerful thing to look at.
Use RTEMS as your Real Time OS. Linux is OK in PCs but is the wrong shape to fit in embedded systems.
the comptuer in my truck is having porblems anyway, how do I find out what I need to control it though?
I presume that I need to put a (variable) voltage/current to the fuel injector, and read all the sensors and decide what to do. How do I go from there to doing it though? What numbers, and how time critical is it. I have a throttel body which I presume has less critical timing requirements, but I need to know if linux will do it, or if I need a more real-time OS.
No playing quake on the system, but I'd know more about what is going on.
BTW, I'm the one who sent this question to Ask Slashdot.
I live in Las Vegas, Nevada, and yes, temperatures in the trunk can reach 100C(212F) in the trunk when the car is parked out in the sun in the summer months when it is 115F outside. The highest temp I recorded in the trunk is 221F, according to my gallium thermometer. Yes, this is above the boiling point of water. Were it not for the antifreeze, the radiator in a parked car with the engine off would boil over (and does for lots of tourists not prepared for the heat!). Welcome to the desert!
Silly side note: The local news ran a story about this woman who bakes cookies in her car during the summer. She puts the cookie dough on a pan and sets the pan on the dash of her parked car while she's at work, a little later in the day, yummy cookies for the office staff! I kid you not!
BTW, I'm the one who sent this question to Ask Slashdot.
I live in Las Vegas, Nevada, and yes, temperatures in the trunk can reach 100C(212F) in the trunk when the car is parked out in the sun in the summer months when it is 115F outside. The highest temp I recorded in the trunk is 221F, according to my oven thermometer (which I tested for accuracy). Yes, this is above the boiling point of water. Were it not for the antifreeze, the radiator in a parked car with the engine off would boil over (and does for lots of tourists not prepared for the heat!). Welcome to the desert!
Silly side note: The local news ran a story about this woman who bakes cookies in her car during the summer. She puts the cookie dough on a pan and sets the pan on the dash of her parked car while she's at work, a little later in the day, yummy cookies for the office staff! I kid you not!
not where are you driving, where are you parking. If you live in phoenix, and you park your car outside in the summer, it can get that hot. . .
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
Just remember that your replacement needs to be 100% reliable. A malfunction could conceivably damage the engine (not to mention the fact that a failure while cruising down the highway could have other disastrous consequences).
But it shouldn't hurt to tinker with. Sounds like fun, actually.
Garages nowadays have computers that they simply hook up to your engine computer. They're able to diagnose a lot of problems that way, since the engine computer can provide the garage computer with tons of data about how the engine is functioning.
It seems to me like this could (and SHOULD) be easy to hook up to your own PC. A lot of the information would certainly help those of us that are capable of making repairs to our own cars.
Not to mention the geek factor...
The ethernet idea is a pretty good idea. You could wire up ethernet jacks in front and for the rear seats and perhaps even one next to the gas cap. It'd be cool to be able to just plug an ethernet cable into a jack next to your fuel port (and what's a more logical place?) to do updates to your car. You could even run Samba on it and have your car appear in the Network Neighborhood for the Windows machines on your home LAN. Or, you know, you could go one step further and get a wireless network card...
I'd be wary, though, of using a 12VDC -> 120VAC power system, since you're just having to drop the voltage again to a low-voltage DC source for use with the computer. Those conversions are going to cost a lot in terms of power and heat. A far better solution is to find some way to stabilize the 12VDC power from the car and drop it to 5V or whatever for use directly with the computer.
Do you have a URL for "Inside Technology?"
I've been working on this type of project for my car, and I've been having trouble finding a PC-on-card with LCD screen support.
www.arisecomputer.com (or something close to that) has some awesome DC power supplies for sale.
www.cellcomputing.com has the REALLY tiny stuff. Pretty expensive, but not really more than $1000.
That seems like a reasonable price to me, dude. Industrial PCs are pretty expensive.
Actually, the only reason that I'm building my own is that none of the other kits have the proper level of display quality that I'm looking for. I definitely want some kick ass visualization on a 6" LCD, as well as touch-screen support.
If you want to talk about this, send me some e-mail.
At the very least, though, let me know the URL for Inside Technology.
Thanks.
This is the goal of the CAJUN (Car Audio Jukebox UNIX) project, isn't it? :-)
PS. I think there may be an update by Monday, but I am not sure.
Take a look at Alpine's solution to the "attractive nuicanse" (sp?) problem: IN-DASH MOTORIZED/HIDDEN DISPLAY!! This is definitely my choice. They have a kick-ass GPS system that ties into the display as well.
Sounds like the requirements for a notebook PC.
Sean
RFC2119
Now you're getting into something considerably more complex than simple stuff like MP3 playing, GPS, and anything else you might normally use your computer for. Check out the diy_efi mailing list (Do It Yourself Electronic Fuel Injection)...you might be surprised how complicated things really are. http://efi332.eng.ohio-state.edu/diy_efi/
-- OpenVerse Visual Chat: http://openverse.com
Well I was getting ready to announce this anyway, so now's as good a time as any...
I've been working on developing hardware and software combinations for about six months now for using Linux in a car. I've recently been given a copy of the TIGER/Line database and am working on a format for storing navigation mapping data in a compact enough format to use in a car for GPS automotive applications under Linux.
There's a mailing list for the project, even though its really in its infancy. The mailing list is meant for discussion about automotive uses of Linux, as well as hardware and software issues with using it in that environment.
Anyone interested should check out:
http://www.bangsplat.org/autolinux
Hugo, empeg
I have a AMD 5x86-133Mhz (486 class) and it plays MP3's fine. AS long as it isnt doing anything else. With mpeg123 running in console it uses about 60% of the CPU power. thats fine if all the PC is gona do it play MP3s.
I have to return some videotapes...
(I can't seem to remember to TAB and not RETURN!!)
When was the last time that you were zooming down the freeway and you wanted to run a spreadsheet? Or play Doom?
There is a time and place for PC's and driving is not one. What you need is a simple computer that only does exactly what you need- that's not necessarily a full pc.
no, take a DiskOnChip, go to m-system
there's industrial SBC (single board computer) or "biscuit PC" that can handle all this
--
"Science will win because it works." - Stephen Hawking
there's 144Mb DOC2000 i think, also i know SBC with 2 or more slot for DOC, there's also add-on card (ISA or PCI?) with 4 or more slot...
however DOC require a slot and a driver, but you can use flash IDE drive, you just plug them on your IDE ribbon and that's it! no movable part, only memory!
--
"Science will win because it works." - Stephen Hawking
I've been working on this problem pretty intensively for the last 2 years for a company that makes automobile navigation systems. We're using Linux (currently 2.0.34) for our next gen version (out later this year). As a lot of people have noted, storage is probably the biggest issue. Its not too hard to meet automotive environmental specs with silicon, but commonly available rotating media are a different story. I'd love to be able to use solid state storage, but both maps (for navigation) and MP3's take up so much space that solid state will not allow us to build an product with an attractive featureset within our target price of less than $1000 (hopefully, a lot less). CD's are more sensitive than hard drives all around, but the failure modes on hard drives are more catastrophic so you need to be extra careful with them. Shock mounting handles this problem nicely and inexpensively in all cases, although building the unit so that your typical auto installer can't kill it by dropping it is still difficult. The bigger problem in the real world is temp. In principle its not hard to make inexpensive DVD's, CD's, or hard drives work over large temp ranges, but nobody does because the volume market is all in office equipment. The stuff that is built for cars is very optimized and not adaptable to other applications by and large (like a data device) - I know, I've done it both ways. In the end, if you want to make something inexpensive you either have to compromise on some things (mainly temp range) or spend a LOT of money tooling up your own storage device.
Our device uses a very fast MIPS processor, has audio on board (the user interface is speech recoginition/synthesis) will come in hard drive and DVD versions, is spec'd to work from 5C to 55C (portable use or car interior, not trunk) and is about the size of a fat walkman. If you are serious about developing software for such a platform contact me, maybe we can work something out.
this is not a sig
I wouldn't even _think_ about attempting this, and I design engine computers. They are far, far, far more complicated that you might thing, especially newer ones which often control much more than simple combustion parameters.
First, you won't be able to do it with Linux, or any other standard PC unix. They simply aren't designed for this type of application. You'd have to go with some kind of RTOS (Real Time OS), and those generally cost big dollars.
Second, there is a huge amount of I/O on an ECU. There's between 1 and 8 injectors, 2-8 ignition coil outputs, air-flow sensor, throttle position, inlet air temp, crank position, cam position, knock sensor(s), and that's just to run the engine. Then there's all the other outputs that the ECU controls.
The environment is very harsh as well. During a load-dump, you will see 50V+ voltage spikes on Vbat. Temp. range for a ECU mounted on the passenger cabin side of the firewall is ~-40C - 100C. If it's mounted in the engine compartment, bump that to 125C. It needs to withstand 2+G of vibration as well.
If you're looking for tuning opportunites, there is probably an aftermarket chip of some kind for your truck. If nothing else, Eddlebrock and Holley are starting to make fuel injection systems.
One question that has come to mind everytime I've looked at CAJUN is "how will they survive in hot weather?" A local video store has a bunch of tapes on display that were melted by being left in hot trunks. While I know that most logic boards are imade of stouter plastics, but isn't there still a lot of potential for heat related damage?
"I once preached peaceful coexistence with Windows. You may laugh at my expense - I deserve it." Be's Jean-Louis Gass
...one of those cheap Multias selling a while back will work well. Grab yourself a power inverter and a pair of speakers, you'll not only have an in-car mp3 player, but a very portable one at that. The friend of mine who has done this wants to fit some small type of monitor, to see what you're actually typing, or rig up something like say to read it back to you.
weeber
Why would you want it that fast? Most MP3s are 128K/s ... so something around 200K/s is just fine. It's cheap (CD media is still something like $2 CDN) and you can fit around 10 hours of music on one CD. I've never understood all these hard drive and flash based things, sure they're shock resistant and stuff, but it'd be much nicer if the OSS hardware building community would settle on a standard for MP3 CDs or somesuch.
... give those old 16Mb simms a home?
You could use less and cheaper non-static ram to buffer the songs a decent amount to make it somewhat skip tolerant
Would such a thing be feasable?
I'm currently working on a nice DC power supply for the car/computer project I'm doing. As of this moment, I'll be using National Semiconductor's SIMPLE SWITCHER LM2678.
:)
Power inverters seem like a stupid waste. DC->AC->DC is pretty silly. And not terribly effecient.
I'm planning on running one of advansys's biscuit PC's, which conveniently only requires +5V.
It wouldn't work out of the 'box' for that, but you could add a MAS3507 (MP3 decoder) and a DAC to get an audio signal. Then just write a little program to send the MP3 bitstream to the decoder.
The CPU is the same one the Palm Pilot uses. It's a great chip for embedded stuff like that. It also needs no cooling, perfect for a car. The LCD drive capability is nice too. Maybe one more chip to control a touchscreen and you've almost got a Pilot.
Simple soultion. Get a small Gell-Cell battery to run it from. Then connect that battery to the car power supply with a charging circuit. Now you have a backup power supply. You need to put good filtering on the supply from the car, large caps should help. Or, better yet, find a way to power it isolated from the main car supply. A switching power supply with a small transformer would do. Most DC/DC converters are built like this.
I used a Cyrix 6x86 at 120MHz (called the P150 I think) and it played mp3's fine, but couldn't do much else at the same time. So unless you're worried about anacron doing an updatedb or something while the mp3 is playing, you'd have to go lower than that to lose mp3-playing capability.
Actually DC-AC-DC is more efficient than a straight DC-DC. However, the NatSemi part is recommended, it uses switched capacitors.
Capacitor switching is the electrical equivalent of using flood gates in a canal when changing aquatic elevations (voltages).
Putting a computer in your car demands a change in the way you think about computing. Especially since most applications are going to be very specific (i.e. GPS or MP3 audio). Connecting a 101 key keyboard and/or a VGA monitor is overkill.
A simple serial or parallel-port based input device is sufficient. Many people are opting for small LCD displays for visual output.
xaudio works *fine* on a netwinder, I'm happy to say. :)
The implementation for the ARM chips uses fixed-point math.
_Deirdre
Check out the mailing list archive at the MadLUG (Madison Linux User Group) website at http://madlug.jvlnet.com. One of our members, who is also a sysadmin at this ISP, has done this rather successfully.
I would check out the companies that make a ruggedized equipment chassis. A lot of them sell CPUs to install in them. You might even find disk drive enclosures that can operate while you're driving (pretty scary thought, though). Someone recommended laptop drives which would be a good idea since their small size should make them somewhat less susceptible to shock problems.
The automotive environment is a very harsh environment to build for (which I'm sure you've figured out) what with the heat, vibration, moisture, and power requirements. Hey! Is NORDEN still building computers? If their's can't run in an automobile...
Hope this works out for you. I'm sort hoping that you'll come up with an optional heads-up X display for the passenger side (for safety reasons, you understand) with a glove box mouse.
CUR ALLOC 20195.....5804M
Agreed about the problems with temperature extremes and HDs. It's probably 140F inside your car if it's locked up on a hot, sunny, summer day. And, at least here in MN, it would have suffer through -20F -30F. A normal HD's not going to survive.
;-)
One thing to think about might be a swappable drive bay. Then you could remove your drive just like you remove the faceplate for the CD player
When was the last time any of you were in a police cruiser? Or a utilities vehicle. They have mobile
computing figured out. You may not like the way they do it however. Most have laptops mounted on a special rig so that it can be accessed from the drivers position. Depending upon the size of your vehicle this could interfere with the passenger. Otherwise its probably the best thing going.
-- Some people say they can tell the time by looking at the Sun, but I have trouble seeing the numbers.
Three problems, temperature, vibration, power.
.... mmmm .. quake on the road :-)
Temperature: The obvious answer is insulation. So, put an ice cooler box for housing the unit in your trunk surrounded with pink housing insulation. That should keep it from getting too hot or cold.
Vibration: The only part of a PC really sensitive to vibration is the hard drive. Make a small wooden box, and suspend the hard drive inside using rubber surgical tubing. I use this stuff as a DJ to suspend my CD players. It's strong enough that it won't break, and is nice and stretchy to insulate againsed any shocks. Put the whole deal inside the cooler box.
Power: You can buy power adapters that should do the 12 to 120 trick at your local electronics store such as Radio Shack. Just note what type of power supply your using. Assuming you don't wont to buy an LCD panel, I would recommend getting a 7" POS terminal screen, it shouldn't suck up that much power. Hell, just find a 286 clunker laptop and rob the screen from that, and hopefully be able to wire it up, or use the whole 286 as a terminal for the real box in the trunk. Cool, wire an ethernet into your car, and have the server in the trunk do DHCP so your friends can come to the car and just plug in their laptops
If you have too much trouble with the power, talk to some of the competition level car audio guys, they're really good at those problems. but the solutions arent that cheap.
You will want a big Sun case that hold noise in. ;-)
I know someone who got a Sun case that was being
thrown away. What you are looking for is in the
style of a little refridgerator. They are cases
that look like mid-towers but they are fatter and
they have a door-like thing on the side. For a
fan you'll want to run a tube offa the car's A/C
system into a hole on the side of the case. Just
put a lot of electric and duct tape on there.
Throw in a tight motherboard, chip, RAM, Hard
Disk, Vid card and sound card and there u go...
You might wanna get a PCMCIA connector and stick
a cellular modem on there too! think about that!
- me...
linuxnewbie.com
I used an LPX case, Cyrix MediaGX 266 CPU/sound/video, 1.6GB HDD scavenged from my broken laptop, and a 10" active matrix screen off an old IBM Thinkpad. The low profile computer case sits under the drivers seat, the screen was built into my dash by a local stereo shop (they also wired the PC audio into my radio speakers), we installed a small APC UPS to filter the power, and the whole thing runs (mostly) off of IBM ViaVoice (yes...this is a Windows95 box). My cell phone hooks up to it for checking email or Slashdot, I run DeLorme mapping software for finding my way around, and I can play Quake in the parking lot while the wife is shopping at the mall.
I can't give an exact construction price since I already had a few of the parts, but I would estimate it somewhere around $1000 and 10-15 hours of labor. Of course, if you wanted to play MP3's on this thing I'd recommend springing for a better sound card (the GX sound support can be shut off).
Oh, and don't flame me for running a Windows PC in my car...I'll switch it over when I see a good voice recognition prog for Linux. I've already found or written Linux replacements for all of my other SW, but the voice rec is the key to the entire operation and I can't do without it.
There is nothing so pathetic as seeing a beautiful young theory roughed up by a tough gang of facts.
chech out http://www.jarcom.com/inmotion/ for a build it yourself DC-DC converter.
While I would agree that the DOS/NEWDEAL OFFICE combination is an excellent low-power solution for running a "modern" OS on old hardware, this solution just doesn't quite give you the MP3 playback capability that we're looking for here. I ran Caldera DR-DOS and NewDeal on my P100 laptop for quite a while and it worked like magic (until I finally installed linux). If you haven't, you should really check out www.newdealinc.com for information on a really awesome alternative desktop operating environment for 8088-80386 PCs (and for people not wanting to run Linux.)
Brought to you by Frobozz Magic Penguin Fodder.
A better suggestion, however, is to just use CD-ROM/CD-R for everything. My vehicle-mounted MP3 box uses a conventional ATAPI CD-ROM drive with a small amount of FLASH disk to boot from, no problems. The "display" uses a BASIC Stamp II Microcontroller, a rotary switch, a couple of buttons, and a two-line LCD I picked up at one of the ham radio swaps in Southern California, and connects to the serial port.
Most importantly, since there are no writable file systems (except for the small RAMDISK I create on bootup), I don't have to worry about power problems resetting the machine. A decent quality voltage regulator supplies 120V AC (although a friend tells me that there is such a thing as a 12V DC computer power supply out there).
I'm working on a webpage for my project, but it's not quite ready yet. Go to my webpage and fill out the guestbook entry there, and I'll get back to you when the page is finished.
Now, to just finish my wearable...
If you really have to have it mounted in your trunk, I would just simply build a small, insulated enclosure with a small blower in it. After a minute of operation, just about any Pentium-class machine I know of would produce enough heat to get the internal temperature of such a chassis to well above 80F. To my knowledge, there is no danger of allowing CD-Rs to freeze, other than concerns about dew freezing on the disk itself.
Lastly, many consumer electronics manufacturers (Kenwood, Sony, et. al.) produce trunk-mounted multi-CD changers. If the environment is good enough for that, I personally don't see any problem with putting a MP3 player in the trunk.
As usual, however, your milage may vary. It works for me.
I'm making an embedded system for my car. It'll have a HUD using bright LEDs. It will perform data aquisition on the car using analog to digital converters, counters, and other gizmos. There will be a microcontroller that runs autonomously, communicates with many ICs over a serial bus, sends data to a PC (when installed) over a serial link, and stores its code in ROM. Most of the components will have an industrial temperature range (from -40C to 125C, or -20C to 70C depending on the part). For power, a 7805 voltage regulator and some capacitors will do.
I'll have this thing attached to my car, on top of my dash. When the car is running, the system will be running (no boot period). And when the PC finally come up (a circut will prevent it when the temp is to cold or hot, then it has to boot) it can get the car's data in real time, and process it for whatever purpose.
I've started working on it. Its quite feasable. I hope to have a test system that will tell me about the pulses going to my spedometer and tachometer (there is no tachometer in my car, but the pulses do make it to the dash).
To make this project possible, I had to get documentation on my car. I connacted Helm to get the service and electrical manuals for my 1989 Honda Civic. I got nice new books that tell me everything I could ever ask about my car -- every electrical circut is fully documented, along with info on how to replace axles and engines (everything is there).
I've already wired up my dash (nothing connected to yet), and made a few test circuts. I'm having way too much fun with this!! So much, that I haven't documented any of it on my web site -- no time!
Anyone else intrested in this microcontroller approach?
"Luncheon meats make the sawdust in your stomach explode."
DigiKey has some devices called DC to DC converters/power supplies. Something like that. The 25W one (most powerful one they have) outputs 5 and 12 volts. I'm not sure if 25W will be enough, but its more than IC's tipically can handle, and you could use more than one unit.
Or, you could try voltage regulators and capacitors connected to computer style power connectors.
"Luncheon meats make the sawdust in your stomach explode."
I have the problem on the other end...
My trunk gets cold and the CD-ROM refuses
to spin up, or when it does, the read is
slow and error-filled. I guess it would be
a good idea to have it copy the files to the HD
then play 'em.
-- Game over man, game over!
I bet people would buy prefab DC PC power supplies
for projects like this. You should sell 'em if you get it working right.
-- Game over man, game over!
An ideal system for this kind of thing would probably be a notebook computer w/ a damaged screen which could be bought for less $$.
-- Game over man, game over!
I've been thinking about doing something like this for a while now. As far as I can tell, the largest problem is the PSU. I could make one myself, but, alas, I'm lazy.... And pretty incompetent when it comes to electronics. Anybody seen a schematic for a 12V PSU? Or, even better, knows of a place where I can buy one...?
I've been looking at an industrial pc-on-a-card from Inside Technology with built-in LCD driver, optional Flash-disk, VGA, serial, Adaptec SCSI, dual ethernet-controller, USB and a 233MMX CPU. Price: about $1000. Is this expensive....?
I've also got a 6.2" TFT LCD-display.... Hmm... If i rip out the ashtray, maybe it'll fit...?:)
This could be the ultimate geek-mobile....:)
I've been thinking of using a DC-DC converter myself, but I'm a bit nervous as to what will happen when I turn the ignition on... The voltage drops dramatically, and you might get some serious trouble keeping the motherboard alive. Could try some large capacitors or sumpthin'.
I've found a compact keyboard just small enough to mount on the glove-compartment lid. Full 102-key thing...:)
I've been thinking of putting the kernel (and some basic utilities) in flash-memory, and using a cd-rom drive to store the MP3's on. To minimize the risk of drive-damage, you could copy the songs to a ramdisk before playing them.
Would've been nice with an IrDA link to connect to my in-house LAN...:)
As to the graphics; I thought it could be nice to be able to use the computer to do more than just play MP3's. I've been thinking of hooking up my GSM phone to it via the serial port (Nokia CDS). I even believe there is a linux-driver for it...!:) Could read my email in the car...:)
Just gotta fix some minor financial problems first....:)
I been thinking about the same thing, though I didn't think about alot of the things mentioned above. I have a pickup so I thought I would rig something up under the seat which contained the board, HD, etc. but I would want to set up a small monitor of sorts into the dash. Where would I get a small enough monitor (5" to 7"). Also, what about input devices, I really don't want to have a full size key board floating around in my truck...I don't have much room to begin with.
PC/104 is a perfect solution. You can find Pentium boards with SCSI, IDE, 100BaseT, and flat panel drivers that run on 5V. Just regulate the 5V from the 12 to get rid of the noise. Then you can throw in a solid state drive and away you go.
:-).
We have a linux box in this configuration running a gun sight off of a FLIR. Works like a champ. I'd like to see a car that can generate as much abuse
There is a huge market of industrial PCs out there. They have all the rugged options that you are looking for.
Flash or solid state disk is the best but expensive. Laptop hard drives on vibration mounts are the next best thing. You can get multiple gigabytes, it's low power (5V only), and it's shock tolerant.
Watch out for high voltage (50V) spikes and noise on auto power.
Check out www.cyberresearch.com and get a catalog (it's better than their online stuff).
The original post said 100C, not 100F. There is a very big difference! The inside does get quite a bit hotter than the outside, but if it ever got to 100C you'd have other things to worry about than the PC in the trunk!
"Those who would give up essential liberty for temporary safety deserve neither liberty nor safety" - Benjamin Franklin,
Basically all you need is caps to stabilize the +14.4V alternator output. Then run that thru a 7805 and 7812 (+5V and +12V) and a DC-DC IC convertor to provide the -5/-12V power. The largest problem is the +5V current. I've made some measurements and it seems to be somewhere in the 3+ Amp range. This can be accomplished by ganging a few 7805 regulators in TO-3 cases which can handle 3A each, when properly heatsinked.
Don't bother with 120VAC invertors, they're bulky and overkill. I also like the idea of using Peltier devices for the heating/cooling needs of the components. Don't forget humidity!
Why don't I just come up with a schematic and post it? Anyone interested??? I'm going to build one for myself anyway.
Greg
I agree with what you are saying about the 7805s in parallel, but the only real cause of failure is overheating. In any event, there are 5A ones available which would be enough current for me.
I was just checking pricing on switching power supplies and while easy, you're right, they're not cheap. I'm looking for cheap and nasty.
I've been working on my schematic based on a previous design I did for a different application, and I'll hopefully have it posted tonight.
Even with the PC104, you'll still have to contend with +5V.
I'm interested in your EFI project. I have a good idea how OEM systems work, and have thought of a few ideas to add to them.
Greg
A number of you have pointed out that the 7805 is incapable of handling the current, and even if it could, it would need a lot of heatsinking. My apologies... I probably should have explicitly said "I know the 7805 can't do the job, but there are 7805 "like" devices that can handle 5A, when properly heat sunk." Everyone seems so concerned about efficiency, but we're talking 100W maybe. Does your car have power windows? Well, they'll draw more juice than this thing ever will. IMHO, I'll take the compactness and low cost of my solution over the efficiency of the inverter-standard PS. Besides, I NEED the heat, since I live in Ontario, Canada, and want to use the final product in the winter.
I've thought about doing a design for a switched mode PS, but here's my problem... The transformer. I'd like to come up with something that we could all easily repeat, and a hand-wound transformer is not that. Anybody got any thoughts???
Greg
I've got an Intel Pentium 90 machine running in the back of my vehicle serving as a mp3 player. The only modification I made to it was to pack the hard drive into a bunch of hard foam within the area for 5 1/4" devices. I stole some foam from hard-drive shipping boxes at work. Before I packed the drive in foam I had to format the drive a few times dew to vibration screw-ups.
For power you should keep the motherboard and such a few steps away from your alternator. This can be done through a number of different methods, I use a 300watt inverter (way bigger than you should need) with a small ups plugged in between the pc and the inverter. Before I put in the ups I had to add another car battery and a battery isolator to fix a problem with the machine rebooting sometimes while starting my engine.
For this project and generally, what are the good parts houses out there? I already know Jameco, but that's it.
For example, the Swiss company Digital-Logic manufacturs various fan-less PC/104 or single-chip modules in the range from 386 to Pentium which can be equipped with 2 to 144 MB FlashROM disk-on-a-chip modules, or even 1" harddrives.
The first thing to pop out of its sockets are always the SIMM or DIMMs, since those kind of sockets are not very resistant to shock or vibrations.
:-(
If you put a anyting on a SIMM or a DIMM into a car, it will have popped out by the time you shift into the first gear.
I would like to know how you where able to adapt the laptop screen to a svga card? I'm looking to install some sorta of flat panel screen for my car computer, and it would be very easy for me to obtain a laptop screen... any info on how you hooked it up would be most helpful!
Thanks,
-Mav
Using flash also goes a long way in solving other problems: a flashdisk draw a lot less power than a regular harddisk, and thus also generate less heat.
Take a look at Jumptec's pages, too. They're the ones that produce the DIMM PC that was features on Slashdot some days ago (world smallest web server). They produce a whole range of PC's intended for industrial use.
Hey,
I have been looking all over for around a 6" LCD
display that takes a standard VGA plug? Where did
you get yours from?
adam@kpower.com
Does the name Pavlov ring a bell?
Why not use a ThinkPad 500 series (or equivalent)?