Thread: Scion xB '06, in-dash Atom 330, Lilliput 889GL; details, pictures, links. Index: pg 1

One More Cable to Go

The last remaining PC wiring is an extension power cable for the DVD. I only need to extend the 2-wire power cable (the 5V pair), which has a Molex 4-pin plug on the end; it plugs into the drive harness.

At installation, I was going to have to wrestle the connection together, because it's way inside the PC. After thinking about it for a while, I decided to do something a little more complex. Instead of finding another female Molex plug and devising a pass-through connection, I disassembled the drive harness at the point where I'd soldered in the 12V fan connection. Then I re-soldered it using all four wires of a long dual-plug drive harness. Where the drive Molex connectors were once short and inside the chassis, the new ones extend well outside the chassis, perfect for hooking things up at installation. I wrapped that whole harness in snakeskin, like I did the cable for the USB hubs.

I'll post a picture of the revised harness.

Now I just have to add a little length to the power connector wires for the DVD unit, add some snakeskin covering to them, and she'll be ready for a test fitting.

That will be the last of the cables. Once I get the extension SATA cables from CPU Stuff, the PC can go into the dash.

. . . at long, long last.

Re-revised Drive Harness

Here's the change I made to the drive harness. It went from this original modification, in which I replaced the floppy drive plug with the two-pin plug for the 12V chassis fan power wires:

Click images to enlarge.

. . . to this new modification, in which I kept all the previous features, and added an extension with two new Molex plugs:

In the second photo, wires come in from the ATX plug (outside the picture on the left), and run to the first of the two short-reach Molex plugs, then go to the SATA plug for the hard drive, and then go to the second unused Molex plug. The old Molex plugs now have protective caps, but I couldn't see a reason to just cut them off; I may find a use for them. Beyond the second Molex plug is the new extension. The yellow and black power wires for the chassis fans are wired in at the point where the extension was added.

The extension came from a dead power supply, and looks different only because I've added snakeskin -- flexible cable sleeving -- to make sure it lays nicely in the PC bay. The extension and the two Molex plugs will stick out the end of the chassis that goes into the dash, and give me a place to plug in the Molex power connector for the CD/DVD drive, plus the Molex power connector from the USB hubs and the touchscreen.

Lengthened Power Wires for the DVD

The last major cable to modify was the power for the CD/DVD burner in the dash. Both the data cable and the power cable started out 12 inches (~30cm) long. Since I'm adding a pair of 12-inch data cable extensions, I decided to add 24 inches (~60cm) to the power cable, too. After soldering in the 20-gauge extensions and covering the joints with shrink tubing, I covered the whole length with snakeskin. I didn't have a single piece long enough, so I put on the first length and added a second piece that overlapped it slightly, then put shrink tubing over the junction, and shrank it down to connect them permanently. Here's the lengthened cable:

Click image to enlarge.

As with other uses of snakeskin, it's there to be sure the cable will slide around easily at installation, and to protect it from abrasion while in use.

That's it for modifications to be made. As soon as the SATA extension cables get here, I can install the carPC in the dash.

Adding a Power Switch for the Screen

I don't really need a switch for the screen; there's already one in the screen itself. But, even when the screen is off, there's a red LED indicator light that stays on, apparently to indicate that there's power to the screen and it's ready to go. And that LED presents a problem: my carPC installation is supposed to be a relatively stealthy one. If there's nothing that stands out when a bad guy looks in the car, it should reduce the likelihood of a smash-and-grab incident. So, if this is going to be a stealth installation, I'd like to be able to shut off not only the image on the screen, but also that LED.

Because I've already made a custom power harness for the screen, I just have to make a break in the positive wire and solder in the switch leads. Then I'll run the leads to a small rocker switch.

The stealth plan means that the best location for the switch would be at the bottom of the dash with the LED indicators, reset switch, and the USB ports. In that area, it would be mostly hidden from sight. A casual glance at the dash won't even pick those parts up, yet they'll be right at hand when I need them.

I've added several things that will be built into the lower dash area, and they're all related to the PC. Although I haven't even laid out a design for the area, I think it's become the PC control panel, by default, so that's what I'll start calling it.

The good news tonight is that the GlobalSat BU-353 GPS head came in today. The SATA extension cables should be in by Wednesday, which means I can start installing parts in the car right now, and the PC should be in this weekend.

Sounds like good news. I'm getting close on mine. I still have a few more components to mount and then the final clean up (wire managment, space filling, sanding, blah blah)

Adding Disconnects to Switch and LED Lines

I'll have wires for the switches and LEDs that that run from the carPC, back into the dash, and down to the control panel below. I want to install the PC end of the wires now, before I install the PC, so I don't have to remove and reinstall the PC to put them in later. That means I want disconnects in those wires so I can connect the PC end now, build the business end into the bezel later, and simply plug in the connections when the bezel is finished.

For example, I put a disconnect in the wires for the PC Power On indicator LED. That system looks like this:

Click image to enlarge.

That's actually a three-wire disconnect that used to be on a server fan. I'm only using the two outside pins. I just happened to have the right wire colors available for the extension, so I took the motherboard connectors off, added the disconnect in the middle, and put the connectors back on.

I've collected more wire-pair disconnects -- some for for four wires each -- so I can have them on all the wires. I still have some soldering to do on the other lines, but first I want to get wire in the correct colors for those extensions, so there's no chance of connecting them improperly.

I also pulled a 10-pin panel-mounted disconnect from a scrapped server. It would be nice to make a single connection to have all 5 wire pairs plugged together without any chance that I mis-connected them, but it would be a major effort to get it to work with this carPC. While I might be able to build that as a rear-panel component that simply plugs into a dash fixture when I slide the PC in, the amount of effort involved at this late stage of the build doesn't appear to be worth it. That's a good part for my next installation. And I'm pretty sure there'll be a next installation . . .

Could I Add a Standby Switch?

The auxiliary battery system will let me operate the carPC continuously, just going to Standby when I leave the vehicle. I'll probably reboot it every few weeks (because Windows just needs that to clean itself up), but possibly less often, depending on experience. So, rather than having to go to "Start - Shut Down - Stand by", I've been thinking I'd like a dashboard power switch that will allow me to easily put the carPC into Standby mode, similar to the process that happens when we close a laptop. That's just a BIOS setting for the action that takes place when we press the power button.

At first I thought all that would take is the revised BIOS setting and the addition of a switch in parallel with the power control wires running between the power supply and the mainboard. Then I realized that setting the BIOS to go to Standby on a pulse would also mean the M4-ATX power supply would have no way to do a shutdown if the battery power got too low, because that same pulse is what it uses, too.

I think the BIOS only offers one setting, so I have to figure out a different system. There's Wake-On-LAN, but I believe that's still dependent on the BIOS setting.

There's too much about this that I don't know, so I have to do some more research on this. Anyone have suggestions?

Why Do I Even Need a Standby Switch?

After writing the previous post, I invested a little time at lunch doing some research into the possibilities of Wake-On-LAN, Wake-On-Ring and Wake-On-Mouse/Keyboard, all of which are supported in the D945GCLF2 board. Tonight I had a conversation with Josh. He thinks I'm chasing an answer to a non-existent problem.

After some consideration of how I'll use the PC, I think he's right on target. Here's my plan: I'm assuming I'll interact with the PC in some way at least every hour while I'm in the car, so I'll set the system to go into S3 Standby -- which is relatively low power usage -- after being idle for 60 minutes. My tests indicated that it can live in a Standby state for several days, and probably much longer, with the auxiliary batteries.

So, when I leave the car, I'll switch the touchscreen off. The PC will go to Standby mode after an hour, but be ready to roll a few seconds after I wake it. That saves any installation of a switch, and allows the M4-ATX to properly control the PC's power.

So, the problem is eliminated by changing my perception -- sort of like changing a bug into a feature by relabeling it, huh?