evaluate this in-dash tablet PC plan
I've been wanting to do something like this for a while, and it looks like it's finally going to happen. I got a Fujitsu Stylistic LT tablet PC (8.4" touch screen, 233MMX, 64MB ram, 10GB HD [could upgrade that later, when I got some dough], USB, tiny black IR keyboard). The whole thing will be able to fit into my dash in place of the head unit and the surrounding plastic. Most of the i/o jacks (including PCMCIA for WiFi + USB2, sound, mic, USB) are on the sides, which, all-in-all, is pretty convenient since the sides of the center console are easily accessible/modifiable.
Pretty simple: take apart the cigarette-lighter connector of the tablet PC's car power adapter, and hook up the + lead to a DPST switch, which will allow to either have the PC on ignition-only or on always-on power, for those times when I might need to use it with the car off. Power saving features of the tablet PC will then be configured to go into hibernation when power is disconnected, or perhaps some more elaborate scheme could concocted depending on how long the table PC battery lasts.
There will be the IR keyboard that came with it, touchscreen, wireless RF optical mouse (not for regular use, just when something complicated has to be done), and multimedia control part of a multimedia keyboard. To elaborate on the latter, for $10 I bought an "HP illuminated USB internet keyboard", the nice thing about which was a large volume control knob, the presence of all the regular multimedia buttons (play/pause, next, etc.), and a 2-port USB hub. If I removed all the other parts of the keyboard, I'd be left with a pretty slick-looking control pad about 5" wide, 2" high, and 1" thick. The keyboard also comes with software that apparently lets you reprogramm all the extra buttons, which I'll look into so as to make me Sleep, Hibernate, Suspend, 'Turn off screen' buttons, as well as buttons to switch to GPS, MP3 or Visualization.
In addition, I plan to use the steering wheel controls. Hopefully, the way those work on my car is by varying resistance across its two wires to indicate to the HU when a button is pressed. It so happens that a standard PC game port measures resistance (joysticks use potentiometers to get X-Y position), which means that I should be able to use such a game port (or rather a USB-adapted version of one since the Stylistic LT doesn't come with one) to get inputs from the steering wheel controls. Anyone done this?
There's also the possibility of using the game ports to measure nearly useless information like inside/outside temperature (using thermistors), humidity, whatever else that can be converted to resistance measurements.
The soundcard output of the tablet PC will be connected to a car equalizer/pre-amp that will boost the weak signal, control volume and split the signal sending it to the 2-3 amps that will be powering the speakers and the sub.
What am I missing? Suggestions, opinions?