In Car PCs

[pugwash]

PLEASE NOTE: SOME OF THIS INFO IS HEAVILY SIMPLIFIED AND NOT TECHNICALLY CORRECT. IT IS GOOD ENOUGH TO ALLOW THE LAYMAN TO UNDERSTAND, DESIGN AND BUILD A PC.

Having recently completed the build of my in car PC I though I would share some of the information and techiques that i used as this has come up a number of times.

I'm not going to cover the pros and cons of in car PCs v Laptops v PDA's, but having had (and used) all three "in-car" I chose to go down the in-car PC route. Laptops are too easily knicked, rather slow for my liking, difficult to repair and always have some sort of drawback, and, whilst PDAs are great at what they do, they don't do a huge amount of stuff that I would like.

So, you've decided to build yourself an in car PC. Now what? Like all home builds you have to decide on a minimum spec based on the jobs PC is going to be doing before you can decide on software and hardware.

For me, my car PC has to be a nav tool (running Memory map, TomTom through an emulator [which takes significant processing power] and ozi explorer), a communication tool able to surf the net at wireless hotspots and talk to Bluetooth phones, and work as an audio/visual supplier able to deal with MP3s and play DVDs. The unit should be as easy to use as possible, small, space saving, easy to hide, and cheap to repair (and not too ugly either)

At this point perhaps I should describe what a typical PC is made up of:

• Power supply: In the home these are pretty big beasts supplying upwards of 600w across a 3.3v rail (for the CPU), a 5V rail (for peripherals and motherboards) and a 12v rail (for bigger peripherals such as fans, CD drives etc etc. You can happily take up 12amps of continuous drawer with a home PC- indeed when i was into "overclocking" PCs i ended up using 2 power supplies to run one PC!!
  
• Motherboard (often referred to as a MoBo)- the heart of the computer- all other bits attach to this in a variety of ways- usually into slots directly or via cables.
  
• Central Processing Unit (CPU)- the brains of the unit, solves hideously complicated equations ("instructions) and does a fair bit of organising. In simplistic terms each CPU works at a certain speed described by it's Hertz value- if a CPU runs at 66hz then technically it can perform 66 instructions every seconds. It's way way way more complicated than that, but you get the picture that the higher the processor speed, then generally, the quicker the CPU will run. Modern processors run at Gigahertz speeds (ie thousands of thousands times per second- well that's what the manufacturers would have you believe). Recent "dual core " processors are basically 2 processors on one chip. CPUs are mainly produced by Intel (who everyone knows) and AMD- who only the techy boys will really use. More specialised CPUs are also produced my a large number of suppliers.
  
• Data storage- Made up of long term storage (a hard disc drive- "HDD") and volatile short term storage (RAM). Think of it this way- imagine every bit of information you have is a book- you would store all your books for long term use in a library (ie the hard drive). But if you knew that you were going to need a few books for a while, you would put those books on a little table so that you didn't have to run backwards and forwards all the time collecting them off the shelves. This little table is analgous to your RAM. The bigger your hard drive, the more information you can store however the bigger your RAM then the less work (ie time) your PC needs to work on something. Both are important. Hard drives traditionally have tiny platter discs that rotate upwards of 7,500rpm. RAM is a solid state memory- ie no moving parts- just like recent ipods. Common amounts of RAM are 1-2 gig, and hard drives can be upwards of 500gig (more on sizes later).
  
• Graphics processor- variously called Video card, Graphics Card, 3D cards, Graphics processing unit (GPU) card etc etc. Takes instructions from the CPU and memory systems and processes them to produce a result on your screen, which will be plugged directly into your graphics card. Pretty much the most labour intensive work for any GPU are games- it's been a good 4-5 years since windows itself taxed a graphics card. Graphics cards nowadays can process upwards of 16.7million colour shades (24bit and 32 bit are functionally the same) and are known as "truecolour" resolution- the human eye "can't" distinguish more shades than 24bit colour. Colour resolution is different to screen resolution discussed below.
  
• Sound Card- much like the graphics card, this processes instructions from a variety of sources and outputs the results to plugged in speakers if you have them. Often built into motherboards now (as opposed to being a seperate "card"), and usually ignored by all and sundry.
  
• CD drive- DVD drive- allows you to play/ record CDs and DVDs depending on what you install.
  
• Flopppy drive- pretty much superceded by USB keys and bootable CDs. Still essential in certain circumstances though. A lot of people take the risk that they will never need one. Floppies only hold 1.44MB- that's pretty small nowadays.
  
• Case- holds all the previously mentioned parts together- can be tiny or huge and come in just about any colour you want.
  

Some interesting info:

• Bytes- made up of 8 bits of data. Unfortunately the PC world quotes speeds in both Bytes and Bits- that's why your broadband connection is a 1meg (ie a 1024Kb) connection but you download at 128KB (notice the different size Bs between Kb and KB- the lower is for bits and the higher for Bytes):- 128 being 1/8th of 1024.
  
• There are 8 bits in a byte, 1024 bytes in a KB(kilobyte), 1024KB in a MB(megabyte- a "meg"), 1024MB in a GB gigabyte (a "gig") and 1024GB in a terabyte (TB). When I built my first computer it had a 1MB hard drive which was considered huge at the time. Nowadays a 1TB hard disc (HDD) is not uncommon (or expensive)- that's a million times large than my first HDD. FYI, every word ever written would fit on a 760MB CD! Images and videos are what takes up space.
  
• You can have a 2gig CPU, 2gig of RAM, and a 20gig hard drive. All mean something different! don't worry about it though- just remember that in general the bigger the numbers the better.
  
• All the parts connect together in a myriad of confusing and bewildering ways. Often it is easiest to buy a "bundle" which contains parts which all fit together and work together.
  
• Static- MoBo and CPUs are physically quite strong, but very very delicate electrically. You can contain a huge amount of charge which can happily destroy CPU circuts and even larger item. PC parts have improved recently, but as minimum I would still make sure you have no strong magnets nearby, you take your shoes off and ground yourself on a piece of earthed metal- exposed radiator metal works well. Ideally you would have electrostatic mats and an earthing strap round your wrist- overkill for home use though. Those little grey/silver plastic bags that PC parts are supplied in are electrostatically resistant.
  
• Clock speed- everything in a PC has to be able to work at the same "clock speed". Memory, CPU, Motherboard- this is usually called a FSB (Frontside Bus Speed)- the BUS being the electrical circuit that connects all the components together and allows them to communicate efficiently and quickly. FSB will often be around from 333 up to 600 or more MHz. Usually the MoBo defines the minimum speed everything works at- you can add units that work at a faster speed, but not slower!
  

There is so much info about PCs and computers, that I have only given the merest backbone here- and probably nothing that the vast majority of people on here already know, but, they are good topics to revisit.

Back to In-Car PCs

The A/V side of things and a necessity to run a notoriously power hungry PDA emulator has meant that I would like to have some pretty strong PC specs. Ideally I would be running 2 gig of Ram, a 3gig dual core intel processor (currently quicker than the AMD offerings), a 500MB hard drive, a pretty beefy video card, etc etc. BUT you have some pretty major drawbacks in fitting a PC into a car:

1. Supply of power- car power supplies are in no way suitable for hooking a computer up to- the spikes and dumps from the alternator caused by starting and stopping an engine would fry an unprotected motherboard in seconds. Even when you use a dedicated in car PC supply you can't really get a reliable supply of more than 180W (as an upper limit). This means you have to pare your specs right back. Performance uses a lot of electricity and produces a fair bit of heat (more of that below)
   
2. Reliability- Cars are actually pretty abusive places for computers- loads of vibration and as well as humidity, dirt and dust- none of which a PC likes.
   
3. Space- unless you want to lose a serious amount of in car space then you need to be looking at mini and Micro PCs.
   
4. Style- ideally you don't want a grey dull PC box sitting in your posh new car- something in keeping the car would be nice.
   
5. Heat- excess heat causes all sorts of problems with a computer- but seeing as you have reduced space for a case then clearing heat becomes harder. 2 ways of reducing heat- prevention or removal- removal is impossible (because you don't have space for the fans), so you have to prevent heat from occurrig!
   

Considering this you are left with a number of conclusions:

1. Keep your specs as low as you reasonably can- lower specs take less power- an older AMD Athlon processor will typically use 14w- a newer Northwood core can easily use 80w by itself, and up to 100w if tinkered with.
   
2. To improve reliability then remove every moving part possible- no critical fans, no rotating assemblies etc etc. No fans mean less dirt gets blow about, etc etc and no rotating parts mean that the PC is impervious to vibration.
   
3. To reduce space you are looking at custom enclosures (or very small metal cases- ammo cases?). And to fit the kit in you need micro ITX form MoBo (ITX and ATX are industry wide sizes of MoBo that show compatibility between cases and motherboards).
   
4. It would be nice to think that your PC did not stikc out like a sore thumb, and could be tucked away somewhere inconspcious- like under the drivers seat! You don't want to drawer attention to it so that it gets knicked every other day.
   
5. Heat prevention is caused by low specs, but also in how you actually build the PC- if you don't do everything neatly and carefully then you prevent huge problems with any heat removal!
   

Software:

I haven't mentioned software anywhere yet, because simply, i am only going to use windows XP. Vista is just too power hungry for low spec PCs to run, and windows 89 and 2000 just aren't stable enough. XP can be made quite small (by using XP lite) and easy to use, but is stable enough (being built around older NT server software) that it won't crash too much and can be recovered when it does. Some of the custom "car pc" software that i am thinking of using precludes the use of Linux (of any sort) or MAC OS, so i won't discuss those here.

Screen:

For an in car PC you really want a touchscreen flat panel TFT monitor. They perform well in low light surroundings and the later ones are bright enough to be seen on a bright sunny day. A touchscreen is superb for in car use because keyboards are just too cumbersome most of the time. You can get touchscreens from 7" upwards. I'm lucky in that i have a couple of spares from work that are 12.1"- nice and big then. Most touchscreen panels also come predrilled to accept VESA mounting plates with 75mm or 100mm holes- this means that you can use standard mounts sourced from Ram Mount or similar

Next Lesson- Component selection, sourcing and compatibility.

.

[GBMUD]

Not many pictures, is there?

Chris

[MudAllOverIt]

Not many pictures, is there?

Here's some of mine then (put this together just over a year ago)...

The motherboard is Mini-ITX form factor -- in this case an EPIA MII 12000 from Via Systems. (1.2GHz C3 Nehemiah processor with 1GB RAM, 100GB 2.5" hard disk, NetGear 802.11g PCMCIA wireless network card and Billionton Bluetooth Compact Flash card. I've fitted it into a VoomPC ruggedised enclosure with an M1-ATX intelligent vehicle power supply.

Pic of the motherboard and M1-ATX PSU fitted to the VoomPC baseplate, prior to lacing and securing the cables:

Pic of the VoomPC main extrusion with the ultra low noise fans fitted:

I've installed the PC centrally (on what's left) of the bulkhead behind the cubby box. The +12V supply is taken directly from the battery (on a fused feed) and the master on/off is ignition-switched +12V. The ignition-switched +12V will eventually be wired into a front console switch so the PC can be turned off "permanently" when not needed.

Picture of the monitor mounted on the dashboard. This is a mess -- still to be sorted. I've a got a MudStuff console that is now ready to go in to tidy it all up and I'll sort out the monitor positioning at the same time.

[pugwash]

Chris,

I have about 4 times the write up to come yet- that was an introduction only.

Bill- nice setup- i see you have gone for CF slot- did you consider using a CF adaptor as a HDD instead of a traditional HDD? Gives some added vibration resistance.

Much more to come guys- including piccies

Jim

[vinyljunkie]

Nice Pugwash

this info really couldn't have come at a better time for me as this is something i have been considering for a while but not had a clue where to start.

Thanks & looking forward to part 2

Dan

[LandyManLuke]

It'd be good to consolidate some decent information in one place.

My write up here

[white90]

Jim

why the odd font?

and where are the pictures of this device?

[MudAllOverIt]

i see you have gone for CF slot- did you consider using a CF adaptor as a HDD instead of a traditional HDD?

Yes -- but wanted initially to keep the CF/PCMCIA slots free until until I'd figured out the final config so went with a conventional laptop HD. The HD is mounted on "isolators" (the manufacturers decsription -- they're actually just rubber grommets ). It does get a fair bit of hammering but so far no problems at all.

Other info I missed on the original post:

runs XP home edition

the monitor is a 10.4" touchscreen job (good price from an eBay seller in Germany)

no mouse or keyboard at the moment but would be interested in a good Bluetooth trackball type device if any exist?

the original Billionton Bluetooth CF card lasted only one outing (got it dirt cheap from an eBay seller in Hong Kong ) and was replaced with a SiteComm Bluetooth CF card which has worked flawlessly

using a Holux GPSlim236 Bluetooth GPS which sits on the top of the dash

Cheers,

[pugwash]

Bill- we've almost got the same setup- my HDD is a little more interesting though- i found a couple of good wireless (RF) trackball small form factor keyboards.

Lanyman luke- loved your setup, would be really interested in the VB code f you don't mind sharing- probably won't use it, but it sounds very interesting.

Tony C- I can't change my post now, but please feel welcome to alter the formatting- i coped and pasted from google docs but don't think it liked it very much.

Piccies to come when i have taken some interesting ones!

[MudAllOverIt]

i found a couple of good wireless (RF) trackball small form factor keyboards.

Any links to info Jim?

Cheers,

[pugwash]

http://www.keyboardco.com/keyboard_details.asp?PRODUCT=186

i have some more links on my PC at home.

They aren't cheap though

[JST]

great post Jim, i am just about to do this.......................

well maybe i will wait until the map and compass dies (even more!)

[LandyManLuke]

Landyman luke- loved your setup, would be really interested in the VB code f you don't mind sharing- probably won't use it, but it sounds very interesting.

I'm happy for you to have a root around the source code, but i make no claims to being a 'tidy' programmer! If you'd like me to tidy it up, or make it a bit easier to follow i'll happily do so, it's been a work in progress for about 4 years now.

[TheRecklessEngineer]

I'm working on one of these too, but starting by cannibalising a laptop with a dead screen...mainly because of price, but also because I have the in-car adapter to sort out the power issues.