1) Introduction
Well, if your can identify yourself in more than one of the scenarios below then you should certainly (at the very least) explore the idea of building one.
• You have this sudden craving to listen to that very Diana Krall single (which you ripped to your home PC last night) when on a long drive
• You are often Lost & confused on your way to that conference center but too proud (or maybe lazy) to ask for directions from locals
• An inexplicable desire to know the exact status of your car’s innards ranging from the mundane ( exact engine RPM) to the exotic ( instantaneous mileage ) to downright geeky (after all, the intake manifold temperature on your car is the perfect conversation starter with the PYT sitting on the passenger seat :lol: )
• Picking up an incoming call on your cellphone without running a risk of coughing up a fresh new Gandhi to the friendly neighborhood traffic cop
• Show off the latest episode of Heroes to your friends in the office parking lot
• Are serious enough about your music to try recreate a realistic soundstage in your car but your efforts are being marred by the inherently bad accoustic setup that plagues car audio
Of course, you could carry a plethora of devices in your rucksack along with a it-broke-my-bank type Head-unit mounted in your car. But face it, don't you wish cheaper yet more effective solution was available (which also has the incidental benefit of incomparable bragging rights.)
Not to mention the additional flexibility and customization opportunities it offers.
2) How to get started (aka challenges)
Now that have you decided to take the plunge, it’s time to set aside a budget and decided on what your carputer (sounds better than a Car
PC, doesn’t it
) hardware and software configuration are going to look like.Building a carputer isn’t very different from that kick-ass desktop you set up in your den, but there are some major differences, or challenges if you will, that are involved.
Power Consumption
Unlike your AC powered home rig, you cannot afford to put that screaming fast but power hungry quad core CPU or Raptor drives here. Your car PC is going to run off your car battery and alternator and you need to keep the current drain on your car electricals as low as possible, yet keeping the configuration powerful enough to allow smooth operations
Human Interface Devices
A 500 dpi laser mouse and the latest Saitek keyboard is all dandy for your den rig. However, you really cannot take your hands off the wheel to enjoy the top notch ergonomic joys of your conventional interface devices when driving the car. Fortunately, there are several other options available, and we will get to them soon (There is a full dedicated section on this later in the guide).
Operating system
Now there are people who are successfully using Linux and OS X on their car systems, But the vast majority of people use Windows XP as their operating system of choice for the simple reason that a variety of Carputer front-end options exist for Windows (both open and closed source) and there is an active base of dedicated as well as open community development efforts available for the Windows platform front-ends. Those being said, if you are still keen to use Linux or OS X (or want to write your own OS from scratch ☺), feel free to use this guide for the hardware section alone.
However, this guide will focus on windows based front-ends here onwards.
Now without much ado, let’s get to the hardware choices first. The software aspect can be handled once the hardware platform is built and ready.
CPU and motherboard
Having said that, the current platform of choice for most people has to be the mini ITX based Intel Atom platform. Not only is it more than adequate to handle XP, MP3 playback, GPS navigation, Phone BT integration etc, it is also cheap, small and extremely frugal on power too. (Did I hear someone say HD playback, sorry, the atom won’t, but then 1080p playback on a tiny low res carputer screen isn’t what the doctor ordered for the Blue-Ray enthusiasts anyway
)If you cannot do without additional computing power, you could also choose the new mini ITX LGA775 offerings from Zebronics and Intel, but be prepared to spend a good bit more on the PSU too (dealt with later in the guide)
If you do however have a Via C7 or AMD Geode board lying around gathering dust, feel free to use it by all means. But if you are buying new, the Intel mini ITX D945GCLF is a no-brainer, really.
Display
From personal experience, a 7†screen is possibly the best compromise between screen real-estate and the limited physical space you need to mount a screen without much trouble in a car. A lot of people use an 8.4†too which is only marginally more expensive.
Both screen sizes are available from Mumbai based firms, amsimpex.com and iride.in and range from 11,000 to 20,000 depending upon your choice of size, brightness and LCD type.
The best screen type for Car usage is the trans-reflective touch screen LCDs that can be viewed even under direct sunlight but they come at a price. I have been using a non-transreflective LCD for two years now and have not found any real reason to upgrade so far.
If you really want to work on a budget, you can buy a composite input non-Touchscreen type LCD for as low as 3-4 K INR at your local car
accessory dealer (they are used as DVD playback screens) and use a VGA- > composite breakout box to run the LCD. However, a carputer without a touchscreen isn’t very convenient. If you are still determined, move on the Human Interface section for more details on how to live
without a touchscreen monitor in your car.
Coming back to touchscreen LCDs, you can also opt for In-dash motorized display units that fit within a single DIN slot in your car and fold out when powered on. (And iride.in does offer a In-dash monitor with a built-in Amp which would potentially cost you the same as buying a LCD and head-unit separately)
A single DIN TS LCD from iride
However, I have heard of several people complaining about the mechanism getting stuck. YMMV.
Most people outside India use Xenarc/Lilliput screens. Although these aren’t available locally, LCDs from iride and amsimpex are fairly dependable, and possibly sourced from the same OEM manufacturers.
If you were to ask for my recommendation, a basic 7†touchscreen LCD with VGA input is your best bet
Do note that most car LCDs have a native resolution of 800X480 pixels but they work happily at a more standard resolution of 800X600.
HDD,ODD and Memory
1GB of DDR2 memory and that’s it. Any less and your system will act sluggish. Any more and your startup time will take a hit since we intend to use hibernate mode.
As for the HDD, do yourself a favor and get a 2.5â€, 5400 rpm HDD , 160 GB ideally.
2.5†HDDs are designed for rough usage and the shocks and heat within your car may tax a regular 3.5†HDD to death quite fast.
As for the 5400 rpm recommendation, 7200 rpm disks are considered more sensitive to rough usage, and the marginally extra performance from a 7200 rpm may not be worth the risk.
The ideal ODD choice would be a slim USB ODD since you can mount one at a convenient location close to the dash and run a USB cable from the ODD to the carputer.
Having said that, I have never felt the need for a ODD in my carputer and don’t have one in it.
Power Supply
A Carputer can use several forms of PSU solutions
• 220 V inverter off the Cigaratte adapter slot: Cheap, but highly inefficient. Essentially you use a regular SMPS powered by the 220V line out from the inverter. Hoever, the DC->AC -> Back to DC conversion is ineffficient. In addition, your carputer will lose power each time you start the engine because of the voltage drop at each crank. Not recommended at all
• 220V inverter off a dedicated power bank circuit: This requires a 220V inverter powered off a 12V sealed Lead-Acid battery (e.g UPS battery) which charges off the car alternator (via a rectifier Diode to prevent the return flow of current during a crank) Although this does solve the problem of restarts during cranks, it brings in additional costs and complexity. I used this setup for a few months, and although it is a usable work-around, I really wouldn't recommend it as anything more than a stop-gap measure.
• A dedicated DC-DC PSU: The most elegant solution for a car PC. Dedicated DC-DC PSUs like the M1-ATX are specially designed to power a PC in an automotive environment. A DC-DC PSU plugs into the 12V power line and provides standard molex connectors with +5V, +12V and +3.3V to power the various subsystems of your carputer. PSUs like the M1-ATX even have a built in tank circuit that allows that PSU to provide uninterrupted power to the carputer during regular cranks.
In addition, DC/DC PSUs automate the startup/shutdown routine of your PC by powering up the PC everytime you start your car and shutting it down when you switch it off.
A SB-80D PDS from iride
I would strongly recommend the usage of a good DC-DC PSU for your carputer. Before selecting the right PSU, please make sure that the 12V power output of the PSU is adequate to power your motherboard.
E.g. The SB-80 PSU available at iride is rated at 5, 5 and 2A on the 3.3V, 5V and 12V line respectively. This is sufficient to power the Intel Atom board rated at a peak 1A on +12V and 4A on +5V. However, this would restrict your selection of usable USB ports to just two (at 500mA each) so if you want to use additional USB peripherals, you may want to upgrade to a 100 or 160W PSU paying careful attention to the available power output on each line.
Other Peripherals
Bluetooth
You would need a BT dongle to communicate with your GPS receiver and phone. Get any cheap 150 INR dongle you can lay your hands on and it would work just fine. Blue Soleil is the preferred BT stack for most car PC applications so make sure you get a Blue soleil supported module.
Radio
Many people use a USB radio module.(although I don’t). In any case, setting up the radio is as easy as procuring and installing a USB radio module and wiring it to your vehicle’s antenna. Your front end will automatically recognize and configure the rest of the stuff.
GPS device
Get any Bluetooth GPS dongle you can lay your hands on (USB would work fine too). Although Sirfstar III chipset receivers are regarded as the best, there isn’t much to differentiate between a Sirfstar or any other standard chipset.
Of course, you would also need a mapping front-end and corresponding maps to handle the map positioning and direction calculation. Read on more about it in the software section of the guide.
You would also need to do a one time pairing up of your GPS receiver with your BT stack and configure it as a Serial port slave. Take a note of the COM port that it connects to and assign the same port while configuring your front-end. (protocol = NMEA, Baud Rate = 4800)
This is what I use:
Microphone
To support phone integration, you would (of course) need a microphone. The best type of microphone for car usage is an array style microphone that help reduce noise and echo
Beware though that phone integration solutions via your carputer are prone to cause echo problems for the calling party, although the problem is easily solved by reducing the volume of your speakers (In case you haven’t figured this already, the calling party’s voice will be output via your car speakers, and too high a volume on the speakers will cause your array mic to pick up the calling party’s voice too
)OBD II
OBD II or On-Board Diagnostics II is a set of standard protocols followed by automobile manufacturers to retrieve information from the vehicle ECU. An OBD II scanner connects to your vehicle’s OBD II interface and retrieves and presents real time data about your vehicle’s internals on your carputer screen.
There are three protocols in general usage viz J1850 VPW, ISO 9141-2 and J1850 PWM. To find out the protocol used in your car, you can refer to the method described here
OBDII - On-Board Diagnostic's System - Does My Car Have OBD-II? The Connector and Communications.
Subsequently, you simply need to procure and attach a OBD II scantool compliant with the protocol used on your car (available with iride), and Voila!
A COM Port OBD II Scanner
Audio Card
Although the integrated audio on the Intel Atom board is pretty decent, many of you may want to explore the option of a high fidelity dedicated audio card for your carputer.
Do keep in mind that your set of choices remain a little limited as a PCI card may be difficult to house within a slim form factor mini ITX casing even with a riser.
USB sound cards like the Asus U1 or M-Audio Transit provide a good alternative, and if you do have a good quality audio setup in a car, a dedicated sound card is highly recommended.
3) Cabinet and Final Assembly
The right choice of cabinet for a Carputer is surprisingly difficult since it needs to be small enough to fit unobtrusively at a readily accessible location within the confined space of a car.
Back in 2007, when I built my carputer, Mini ITX cabinets were unheard of in India while being pretty expensive (for a cabinet) in the US. I eventually ended up building my own chassis on a laminate board housed in a cardboard shoebox.
Shoebox PC hyeah:
Thankfully, mini ITX cabinets are relatively more easily available now at reasonable costs locally. The Zebronics Chotu at ~2K seems to be a good fit being small and unobtrusive enough to fit under the driver passenger seat (I only wish it had a better name)hyeah:
A more convenient (if not better) alternative
If you are planning to use PCI cards like a PCI sound card, you may need to look at other alternatives though.
I am assuming you are familiar with assembling a computer so I will skip the details of making the connections. However, here are a few aspects that are unique to carputers.
• For mounting the HDD, buy a cheap (and thick) silicone cover for an ipod nano or similar. They are readily available at your local neigborhood electronics store for less than 50 INR. Cut out small grommets similar to the one below and mount your HDD on top of these.
This would help your HDD easily handle the shocks thrown around at it courtesy the crater sized potholes of our mean Indian streets
• Read the manual with your PSU carefully. Most DC-DC car PSUs come with a configurable jumper that will allow you to select the power down timings which ranges from 1 to 30 mins (Setting the time that the PSU stays on after vehicle power-down). Set the jumper appropriately. I use a 2-minute setting since 2 mins is sufficient for the PC to elegantly shutdown.
• When wiring the PSU, you will also need to connect the power up/down connector from the PSU to the power on/off connector on your motherboard. This connector is what enables your PSU to intelligently power on or shutdown/hibernate your PC based on the ignition key status.
• To minimize the startup time on your PC, I recommend using a WinLited version of XP to remove all non-essential services and components. Google for winlite if you need additional details
• After you have installed XP and the required drivers, treat yourself to a tequila shot (or Orange Juice) as you are (only) 30% done
4) Front End Selection
As stated before, we shall limit the guide the front-ends available for the Windows platform only. Although there are options including but not limited to Media Engine, Frodo Player, Street Deck etc.
However most of the action (and active development) seems to be limited to two choices, RoadRunner (FOSS, or at least was FOSS) and Centrafuse (Paid) In addition, I have personally used both the front-ends so here is my unbiased take on both:
i) RoadRunner
Roadrunner, recently renamed to riderunner is possibly the most powerful and highly customizable front-end that you can lay your hands on for your carputer.The main developer recently sold the rights to roadrunner to a private firm but a free version of the application is still available (and they claim that a free version will always remain available, yeah-right!
) Anyway, Roadrunner was, and still remains a great front-end for a Carputer with fully customizable skins, support for various different plug-ins. and complete flexibility of implementationHere are a few sample screenshots
