Background As a computer geek, I have always been

Background
As a computer geek, I have always been interested in the concept of using a computer
in the car. I had, on occasion, used my laptop for smaller tasks but had never really
seriously considered the permanent installation. There were always a couple of things
holding me back. The first was space and the second was power. I have no hesitation
about replacing the head unit or speakers in a car, in fact, it is usually the first
modification that I do.
My personal opinion on this matter is that I would rather have a great sounding stereo
system that is blended into the vehicle in a un conspicuous way than a complete fullblown custom installation that has everything on display. Don’t get me wrong, I totally
respect the amount of effort and work that goes into that type of system but for ME only,
I would prefer sound quality and stealth. Again, this is only my opinion so don’t flame
me! Usually, I research the vehicle I am interested in buying so that I know what audio
component upgrades will be possible.
So back to the space restriction. Until very recently, computer motherboard sizes have
been large enough that their placement in a car restricted you to either mounting them
and their peripherals in the trunk of the vehicle or fabricating some elaborate
concealment enclosures. Lots of people have went this way, installing a ‘normal’ sized
PC in the trunk and controlling it remotely. I have seen fantastic installations like this.
Lots of creativity has went into them. For anyone that has a trunk, this is a great
solution. I will explain why this did not work so well for me in a minute.
Related to the space restriction is the power consumption problem. Large motherboards
with 3½ hard drives and big CD-ROM drives consume lots of power. As long as you can
keep the vehicle running this is not a problem but how do you handle the reverse
battery protection, cranking condition, auto startup and shutdown, etc. Until recently,
products did not exist to handle this situation.
About the time that I got interested in in-car computing, a few things happened:
1. The Mini-ITX motherboard was released – this addressed both the space and
power concerns because the motherboard had a very small package size but
had integrated video, audio, LAN, USB’s, Firewire, etc. It was almost a selfcontained computing platform. It also had the advantage of having very low
power consumptions.
2. 7” touchscreen LCD’s became available mainstream – this LCD was a great fit
(in my opinion only) for an in-car solution because it was large enough to see
easily, small enough to be unobtrusive, low power and low cost.
3. In-car power supplies – lots of people smarter than me decided to capitalize on
this hobby and designed and marketed power supplies that could address the
needs of an in-vehicle solution.
So I decided to jump into the water and build a system. Because my personal time was
limited at first (due to family and job) I decided to go the quickest route with the idea that
I would get my feet wet, reevaluate and redesign in the future. I did a lot of research on
MP3CAR and other sites and decided on the following configuration:
Via EPIA M1000 motherboard
Lilliput 7” touchscreen
Panasonic CD-RW/DVD-ROM slot load combo drive
30GB Hitachi notebook harddrive
512 MB Ram
Casetronic C134 computer case with power supply
So I bought and assembled everything. Installed software and stuffed it in the vehicle (I
will talk more about that). I bought and modified a GPS vent mount and mounted the
LCD to the AC vents centered above my radio. I built a makeshift center console
between the seats for the computer and used an AC inverter to power the computer.
Luckily my vehicle has a factory installed 3.5mm stereo input which I used to get the
sound from the PC into the audio system. Everything worked but…
1. I had wires and cables running everywhere! Every time someone new got in the
car I had to hear the comments about how ghetto it looked.
2. The computer was in a very hostile environment. I had a 3 year old and an 8 year
old at the time ( I still have ‘em but they are older now). It was impossible to not
get chocolate milk or Sprite on the computer. If anything spilled, it went on the
computer.
3. The LCD was much heavier than the GPS mount was designed for so the thing
constantly shifted and moved and vibrated. It even started to wear away plastic
on the dash with its constant movement.
So I used it this way for a few months but it did not take long to become unsatisfied with
the way it was installed. So began the desire to come up with a better solution. Pretty
quickly I came up with a few requirements for the second version of the in-vehicle
computer, now designated CarPC v.2. Those requirements were:
1. Touchscreen controller and display should occupy the factory radio location in a
manner that replicated the factory look.
2. Any wires and cables needed must be 100% hidden.
3. The shutdown and startup process will be completely controlled by the vehicle
key position and state, meaning if you turn the key on, the CarPC comes on, if
you turn the key off, it goes off, safely and reliably.
4. Any functions of the CarPC must be able to be controlled via the touchscreen
only.
5. Power consumption should not present a hardship to the vehicle charging
system.
6. Must have a method to get data into and out of the CarPC.
Some additional things that would have been nice but optional:
1. Provide a means to monitor vehicle data statistics via the CAN interface.
2. Should have the ability to monitor a backup camera.
3. Should have the ability to watch movies.
The Vehicle
Let’s talk about the vehicle because this is one of the controlling factors to the design
and installation of the CarPC. The vehicle is a 2004 Honda Element. It is an EX model
with AWD and a manual transmission. I know, people either love ‘em or hate ‘em. Not
much in between. I happen to love ‘em. It fits my lifestyle. My girls love it.
This vehicle does present some serious challenges to my goals. Let’s explore these in
more detail:
1. The audio system – from the factory, the car came with an in-dash cd player with
an Auxiliary sound input. There are speakers in all doors, tweeters installed in the
windshield pillars and a subwoofer mounted below the dash, under the shifter.
When I bought the car, I replaced the in-door speakers with Polks. The sound
was greatly improved. Now the challenges:
a. The M1000 can output 5.1 audio or 2 channel stereo. With the 5.1, there is
no need for the center channel when playing music. The 2 channel needs
to be split into a front and rear and a subwoofer channel.
b. The subwoofer itself is a single voice coil design. This means that I need
to process the 2 channel output into 6 channels(front, rear, sub) which is
easy to do with commercial signal processors and then combine the 2 sub
channels back into a single input to interface with the factory 5-channel
Alpine amplifier. This is not really a huge deal but it is another piece of
hardware that must be dealt with.
2. Dash design – The Element is a little bit unique in the dash styling around the
radio. Most vehicles that use a double DIN radio have a flat rectangular face. In
this way, you can replace the factory radio with an aftermarket double DIN radio
and be assured that the look will be right. The Element radio has a front face that
has a curved profile. A standard double DIN face does not look right in the
Element. The radio is also unique in that behind the front face of the radio the
dimensions conform to the double DIN standard but the face itself is almost an
inch wider than double DIN. I am not sure if it is visible in this picture. I will take
another one of the radio itself.
I pulled the radio to check behind it and the dash is also very shallow behind the
radio. I was hoping that it would be a cavern that gave me lots of room for mounting
things. Not so. I don’t know if you can tell from this picture or not. There is very little
space to work with so everything will have to be compact.
3. Additional hidden space – the Honda Element is a great vehicle but it has no
trunk, no storage really except the glove box. This means that it is going to be
tougher to hide everything.
The Design
Taking all of my requirements and the limitations of the vehicle into account, I concluded
that the best solution for me was to install the entire CarPC behind the LCD and utilize
the space vacated by the radio. Geez it was going to be a tight fit.
The first thing I did was to investigate which pre-fabricated components might work in
the E’. There is a guy on MP3CAR(www.mechatroniks.com) that has a kit for sale that
will allow you to mount the LCD in an Aluminum faceplate and the M1000 inside the
chassis. The kit is designed and constructed well. He also has great information about
how to disassemble the Lilliput and mount it in the chassis. This would get me pretty far.
Guess what? Due to the wider Element radio, the kit would leave a huge gap around the
faceplate. It was also too long to fit the depth of the Element dash. The kit would not
work at all for my car.
Next I checked out the MP3CAR forum started by blk02si that documented his install in
a Mustang. He was doing almost the same thing as me. His approach was to use a
aftermarket install kit and mount the LCD and then attach this to a U-shaped chassis.
His install is AMAZING!! Sounded smart so I bought 3 different aftermarket stereo install
kits from Metra, Scosche and a generic brand. I disassembled the LCD and studied a
way to mount the LCD into the install kit. I could think of no good way to do it and make
up the huge gap around the faceplate. Crap! That meant a custom faceplate was going
to be needed. Since the U-shaped chassis were not sold separately, that meant I
needed a custom one of those too.
I was not too daunted by that. After all, I am a design engineer at a company that makes
OEM automotive components. Design is my life, but I am also on a different budget as
an individual so I needed to keep the costs under control. I would have been extremely
easy to design something that I could not afford to build.
So I pulled the radio, measured the thing accurately, especially the curved and widerthan-normal faceplate. I also modeled the dash cavity, taking into account the cables,
vents, etc. that needed to be accounted for. Using my preferred 3-D modeling software,
I modeled the maximum dash volume that I had as a package constraint. It looked
something like this…
Notice the slightly curved front and the overhang of the faceplate.
The guy that designed the kit for sale on MP3CAR had already modeled the
motherboard and the LCD and he made them available on his website. I downloaded
these. I also found a model of a 2 ½ “ notebook harddrive. I modeled the power supply
using dimensions found in the documentation.
Using the models and my maximum envelope, I designed the CarPC using a tiered
approach to the components. My plan was to put the hard drive and the power supply
on the lowest level. Above that was to be the motherboard. I imagined that this would
allow the hard drive to dissipate heat through the chassis and the motherboard to
dissipate heat to the open dash cavity above. In this original design, the LCD controller
was mounted to the back of the LCD. My original design looked something like this:
My original idea was to build the faceplate using plastic. I have a connection at the
University of Louisville rapid prototype center. With the 3-D model, he can generate a
stereo lithography part that could be sanded and painted. I ordered one and tore apart
the LCD to look at the controller board again. Ugh!! I had not adequately allowed for the
air space needed behind the controller board. After I moved the motherboard to account
for this, the chassis was too long. I would never get it in the dash! Here are some
photos of the plastic bezel.
The plastic bezel had significant warp and the surface was going to require significant
sanding. That and the clearance problem sent me to design level 2. Design 2
incorporated the curved shape that matches the dash and provides more clearance
behind the LCD. This design also moved the LCD controller board from a vertical
position behind the LCD to a horizontal position between the hard drive and the
motherboard. In this way, I could make the overall chassis length short enough to fit it
into the dash. Here is a view of Design level 2.
Fabrication/Build
At the end of deign level 2 I got an offer from the machine shop in the plant that I work
to machine the bezel out of Aluminum with a shot-peened finish. Based on the warp in
the first plastic part I jumped at that offer. They did fantastic work and fabricated the
bezel for me. Here are some shots of the new bezel. The last picture shows how well
the curve contour matches the dash of the car. That dark grey ring is the trim surround
off the dash.
Here is a better picture of the part as designed. Pay careful attention to the small recess
in the top inside edge. This is needed to provide clearance for the touchscreen ribbon
cable.
After the part was provided to me I drilled and tapped all of the holes.
The chassis was intended to be cut and bent into a U-shaped chassis out of Aluminum.
Here is a shot of the part as designed:
I had another contact that agreed to waterjet cut the parts for me. I sent him the CAD
models and got back this:
The parts looked awesome and super accurate! I took them to the sheet metal brake to
bend them and UGH! They had used heat treated aluminum. The part tab broke right
off! They would have cut me another one but I did not want to wear out my good fortune
so I opted to cut the chassis into two sides and a bottom and re-attach it all with angle
brackets. I fabricated my own from a ‘stick’ of ½” X ½” aluminum L-channel.
This turned out to be a life saver as I tried to route cables and wires later and worked
out the positioning of the components. I am sooo glad that I needed to cut that chassis.
Mounting the LCD
I fully disassembled the LCD from the plastic housing. The cables to the touchscreen
and the LCD controller board are attached using small Molex connectors. I carefully
pried these off their boards and started pushing them through the plastic housing. The
USB connector popped right out as it was only 4 conductor. The video cable which
attaches to the controller board was much wider and would not push through easily. I
gave it a little pressure and it popped through but one of the wires got hung and pulled
out of the connector! I should have just split the plastic shell. It was not as if I would ever
reassemble the LCD. Here is a crappy cell phone picture showing the connectors. Not
sure if you can make out the repair or not. It was to the green wire.
In order to mount the LCD in the bezel, I used some dense black spongy shelf liner cut
in strips to cushion the LCD in the Aluminum. You might be able to see it in the picture
below.
For the retainers on the back side, I fabricated hold-downs using scraps of the Metra
radio install kits that I had not used. This photo kind of shows the retainers. They are
also cushioned by the shelf lining material. In this photo you can also see the ribbon
cable that goes to the touchscreen.
So after mounting the LCD, fabricating the L-brackets to hold the chassis together and
attaching the chassis to the bezel, I ended up with a part that looks like this:
LCD Cables
Anyone that owns a Lilliput knows that the cable that connects the LCD to the computer
is about 22 feet long. Not really, it is more like 6 feet but I struggled with how I was
going to coil up this cable inside the dash. I had to remind myself that I will never
reassemble the LCD to its original condition so why not just shorten the cables to the
minimum needed to connect to the motherboard. After all, that will only be about 1 foot
maximum.
I cut off the USB connector that connect the touchscreen to the motherboard and
ordered a replacement VGA socket. I also cut the round connector from the cable that
connects to the touchscreen and the LCD controller. I then soldered the new VGA
connector and USB cable on.
The result was a cable that was only about 1 foot long and would perfectly connect the
LCD and touchscreen to the motherboard.
Another cable that had to be addressed was the ribbon cable that attaches the LCD
controller board to the LCD panel itself. Because I had the relocate the controller board,
the ribbon cable was not long enough to connect the 2 components. I ordered a
replacement cable from www.digitalww.com and installed it. I took pictures to help me
re-orient the new cable but when I went to install the new one I could not get the LCD to
fire up. There are a 4 different ways the cable can be attached and it took me a while to
get the orientation correct. At the same time, I had not anticipated that the small PCB
that contains the LCD buttons had to be connected to the controller board and that the
PCB must be grounded!! I thought that my controller board was toast. After I attached
the PCB with its ribbon cable and grounded the PCB to the chassis, the LCD fired right
up. The first thing I did after this was to reprogram the controller board ROM so that the
LCD will power up when 12V is supplied to the LCD. The instructions on how to do this
are found on one of the MP3CAR forums. After I did this, I disconnected the PCB board.
The cables for the backlight and the touchscreen were long enough, no modification
needed. I just zip tied the cables for strain relief and they were good to go.
Next I needed power to the LCD. Since I was using the 90W M1-ATX power supply, and
I was not using a CD or DVD drive connected directly to it, I decided to use the 12V rail
from the power supply to power the LCD. I bought a floppy disk extension cable and cut
the end off. I soldered the 12V lines to the LCD controller and the 5V lines to a cable for
a purpose that I will explain later. In this way, I will have a regulated 12V and 5V supply
that is active when the power supply is active.
Power Supply
The power supply I used is the M1-ATX. It is a 90 watt power supply with a shutdown
controller. Since I am not using an internal CD-ROM or DVD-ROM, I think that a 90 watt
power supply is more than enough. A quick calculation confirmed that I should never be
operating above 50W under the most extreme condition. The power supply requires 3
input line; a constant 12V power line, a ground and a switched accessory line. The
power supply has blade style terminals with push on connectors, like this:
The last thing I want to do is to remove the CarPC because one of these lines has
vibrated loose so I soldered the lines to these terminals and zip tied them all together.
I then mounted the power supply to the center portion of the chassis on insulated
standoffs.
Hard drive
As I mentioned previously, I chose a notebook hard drive because I wanted something
small, quiet, with minimal power consumption and high shock and vibration durability.
Sure, they are a little more expensive than a desktop hard drive but I thought the
expense was worth it. I chose a 60GB Toshiba. It has great shock resistance, 5400rpm
spin speed, 8MB cache and 60GB is quite large enough for me. The bottom of the hard
drive has super-short aluminum standoffs but just to be safe, I floated the drive on nylon
washers before bolting them to the chassis from the underside.
Motherboard mounting
The redesign of the bezel after I received the chassis completely fouled up the intended
mounting locations of the motherboard in the chassis. I mounted 2 L-shaped rails to the
inside of the chassis and then mounted standoffs on the rails to support the
motherboard.
Luckily there is enough room to snake all of the cables from the bottom layer to the top.
With the motherboard in place, I started making connections to get something that
looked like this:
Notice in this picture how the power cable snakes up from the bottom level to the
motherboard. It tucks nicely between the USB riser and the Parallel port. Also notice
along the right side, the red and black wire is the turn-on switch coming from the power
supply. Also notice the route of the USB cable coming from the touchscreen. It attaches
to the secondary USB ports that are on the center of the motherboard. The other center
port connects the USB Bluetooth adapter. It is a Linksys. One of the best I think
because it supports the latest Bluetooth protocols and has an aimable external antenna
for maximum range. Again, I think it is the best. Worth the extra cost if you want
maximum range, which is EXTREMELY important to me! You will see why later.
Operation
With just these connections and after a little hardware debugging, we have:
Success!!
This is the Windows XP setup screen formatting the hard drive. XP was installed and all
of the VIA updated drivers were installed.
From this picture you can see that with the hard drive spinning continuously installing
software, the power supply was registering 42 watts of power.
Next, the USB hub that is to be mounted in the dash was attached to the intended port
and the WiFi card was attached. You might remember that my configuration needs 4 full
time USB ports and at least 2 free to connect other external devices. These are:
1. touchscreen
2. Bluetooth adapter
3. WiFi adapter
4. XMPCR - this is a XM radio adapter for PC’s that interfaces to the PC via a USB
to control the tuner and a Line-in for the audio.
I caught lots of grief from people for not including an internal CD-ROM or DVD-ROM. I
never really understood that. I can move all of the music, movies, etc. onto the CarPC
with a USB memory stick or external hard drive or I can rip movies or music using an
external CD-ROM drive. I surmised that as long as I had 2 free USB ports I do not need
the built in drive. Anyway, that is my opinion and I am sticking with it. So I needed a way
to get 2 extra USB ports. Using a 4-port hub, this will give me 3 extra. Perfect!! Here is
where the extra 5V line that I mentioned earlier comes in. As you might know, some
devices that connect to a USB port are lower current devices and others are high
current devices. As long as you are connecting low current devices to a hub or a single
high current device, the hub can get all of the power it needs through the USB cable
from the motherboard. As soon as you plug in high current devices, you usually need to
connect external power to the device or to the hub itself. It so happens that almost every
hub uses 5V to power the hub. So with an extra 5V line from the power supply, I can
power the hub or provide power to the device directly. Notice in this picture the red and
black lines entering the hub.
This hub had a small connector so that an external 5V supply could be attached. I
cracked open the hub, desoldered the connector and soldered the wires directly to the
pads on the circuit board. I then sealed it back up. Now the hub is always powered!
High and low current devices are now welcome.
Here you see the USB WiFi adapter. It is a cheapo Belkin from Walmart. No reason to
spend much money on these, the technology is pretty constant across different makers.
This will be the permanent home for the WiFi adapter and the whole hub will be
mounted high up inside the dash to maximize reception.
This is the device I am using to get data into the CarPC. It is my old slot-loading DVDROM drive but now mounted in a sleek external enclosure. This will fit nicely into the
console or glove box in case I need to rip a CD. Otherwise I will just use a USB memory
stick.
Vehicle modifications
When I started this venture I wanted to keep the outward appearance of the vehicle
unchanged. Something happened that changed my mind. My only complaint with the
Element has been the lack of storage inside the vehicle. As you might know, there is
really no center console in the Element. It is just a plastic cup holder on the floor with
the emergency brake in the center. In 2007 MY, Honda added a more street version of
the Element called the Element SC. This version has a very nice, very large center
console with lots of storage options. Since the Element chassis has been unchanged for
several years, I had no doubts that the SC console could be adapted to my vehicle. I
found a guy that was selling the complete console on eBay for $170(compared to over
$650 buying it new from Honda) so I bought one and spent a few days installing it.
The Element has a single factory mounted subwoofer that is below the shifter, kind of
tucked under the dash. Since I had all of the trim off to install the console, I pulled the
subwoofer to see if there was any room behind it for some components. It turned out
that there was a large spot behind it where the XM-PCR would fit and stay nicely out of
sight. Here is a picture of the XM-PCR mounted behind the subwoofer.
Since I had so much of the interior removed I thought I may as well run the XM antenna
cable through the car and out onto the roof. I had been just leaving the antenna on the
dash. Reception was always fine but it looked terrible. I removed all the rest of the
interior plastic trim parts from the driver side of the vehicle and ran that antenna behind
all of the panels, up and under the weather stripping in the hatch and under the large
plastic roof garnish. The antenna has a strong magnetic base. Here is the location of
the antenna.
I reinstalled the subwoofer and finished the installation of the console. What this gave
me was a very convenient place to mount my USB ports in the car and also a nice place
to mount a 5V access point. This picture shows the USB ports and the 5V access port.
The USB ports are under the protective caps.
The next problem that I had to deal with was the signal processor. I was all set to buy
an electronic crossover and use the set it and forget approach by mounting it up inside
the dash somewhere when I found an 11-band Alpine equalizer in my extra parts bin in
the garage. It worked perfectly but where to mount it? The only place that I could find
where it was out of sight but accessible was the glovebox. I had to drill a hole in the side
of it to get the cables in and out of it. The finished product looked like this:
It is invisible with the glovebox closed and works great. I have been connecting my
phone, PSP, iPod, whatever to it to have music in the car until the CarPC is installed. I
am not really satisfied with the look when the glovebox is open so this will be an
improvement item for later.
For power to the equalizer, I used the power cable that had been used to power the
factory radio. It was already fused and unused after removing the radio.
For power to the M1-ATX, I used a vacant 12V power port that I found on the fusebox. It
is fused under the hood at 50A. Should be plenty of power for the CarPC.
The M1-ATX needs an ACC Line(12V switched power) to startup and shutdown the
computer. The factory wiring harness for the radio had one so I used that one.
As I mentioned, the CarPC outputs a 2-channel stereo output through a 3.5mm stereo
plug. I bought a cable that adapts the 3.5mm to 2 RCA plugs for the right and left
channels. These RCA’s were attached to the inputs of the equalizer. For the front and
rear output channels, I fabricated 4 RCA cords with bare wire ends and soldered these
to the inputs of a Metra radio harness. Since the equalizer sends out a left and right
channel, I used a splitter cable to join the left and right channels together for input to the
factory subwoofer harness.
While I was finishing the CarPC fabrication, I used my PSP as an MP3 player by
connecting it into the 3.5mm stereo jack and it sounded great. I adjusted the equalizer
for the acoustics of the Element and left it alone.
Here is a picture of the first fitment of the CarPC in the Element:
I needed to put it in the vehicle to get the mounting tabs cut and installed on the
chassis. This is a shot with the mounting features installed:
Installation
Before the installation, I located a position for the USB hub and all of the needed 12V
and ACC connections. I mounted all of those things and zip tied them all so that only the
plugs that attached to the computer were visible. I removed the center dash garnish to
make positioning and electrical connections easier. Element owners!! Don’t be fooled by
anyone that says that you cannot remove or install this garnish with the radio in the
dash. That garnish pops right off with no interference with the radio. This gives you free
access to all of the space above and below the radio.
After all of the prep work that had been done on the car and the CarPC, the installation
went rather smoothly. Nothing to do but connect the +12V, the GND and the ACC line
and then the audio connector. When I turned the key on, everything booted right up.
When the key is turned off, the computer waits and then shuts down. I have a low
frequency hum that seems to be tied to the spinning hard drive and one USB port in the
console seems to be dead but otherwise, it works as expected. Here is a shot in the
dash with Roadnav running.
Here is a crappy, fuzzy shot of windows loaded. Sorry for the poor picture quality.
Any of you Element owners notice anything funny? Here is the picture from the first
fitment again.
I really liked the black finish on the center dash garnish from the 2007 Element and I
liked that rectangular opening between the vents so I swapped that as well. Why the
rectangular opening? Well, when I use my Bluetooth GPS receiver it would be nice to
not need to rely on battery power all the time. So in a future update, I plan on installing
another 5V regulated receptacle in that rectangular opening for when I use the GPS.
Updates
1. I still have that annoying low frequency hum that is associated with the hard
drive. Not sure if the mechanical vibration is being picked up by one of the other
components and transferred to the audio system. Another thought may be the
electromagnetic interference is coming from the hard drive and picked up by the
LCD controller board. They are in close proximity. I need to pull the CarPC and
start checking grounds and also check the vehicle for improper grounding. I have
also bought a Turtle Beach USB audio adapter. After I eliminate ground
problems, I may try that device. If I plug the audio output into a set of amplified
external speakers instead of the vehicle, there is no noise so I really suspect the
grounding problem.
2. The M1-ATX power supply has stopped providing a 12 ACC on to switch on the
amplifier and equalizer. May have fried the logic in the power supply.