Sensor group
Sensors give your Car PC information about the environment. There’s almost no limit to what sensors you can hook up. Many of them would even be useful:
Engine monitoring — The On-Board Diagnostics II (OBD II) specification provides a reasonably standardized interface to the engine computer in your car. (We only say reasonably standardized in that individual manufacturers define their own diagnostic codes in addition to the standard ones.) We wrote about how to attach a data logger chip to the OBD II port in PC Toys (Wiley, 2003); you can also attach a direct port-to-PC cable to get diagnostic data in real time.
Keyboard — It’s pricey, but L3 Systems makes a QWERTY keyboard you can strap to your forearm. That’s not a great idea for the driver, but it could be convenient for a passenger, although touch typing becomes out of the question.
Radar detector — Although radar detectors such as the Valentine One and Escort 8500 don’t provide ports to interface to PCs, you could mount photocells next to their indicators, wire in a small microphone with a filter for the frequency of their alert, or tap the internal display circuitry to detect voltages sent to the indicator LEDs. Any of those signals could be processed in the PC — for example, to map radar trap locations (combine the data with theGPS location) — or mute the stereo to make sure you hear the alert.
Security — Wiring your PC to monitor the door switches or indoor lights lets it know if a door was opened while you were away, and if you wired in a siren is the start of an automotive security system. The PC has to remain on or be turned on by the monitoring hardware for this to work, so you’ll either need some more complex electronics or have to solve the power consumption problem when the car’s turned off.
Soft gauges — The OBD II port makes data besides diagnostics available in real time, such as vehicle speed, battery voltage, and others. Inputs you want that aren’t available from the OBD II port (oil pressure and temperature, perhaps) are accessible by attaching sensors to the car and monitoring their readings from the PC using USB analog and digital interfaces such as the Phidget 8/8/8 described in Chapter 4.
Touch screen and buttons — The Lilliput LCD panels include both a touch screen and buttons at the bottom of the panel. The touch screen simulates a mouse to the PC, and you can program the buttons to activate functions in your software. If its cost isn’t a problem (think $1,500 and up), an interesting alternative to a built-in touch screen LCD would be the Wacom Cintiq, which is a drawing tablet with a built-in LCD. You use the drawing pen as a mouse, too, so it’s a combination of input and output device that sits in our navigator’s lap. Best of all, it uses standard video interfaces, requires no integration into the vehicle dashboard, and can be safely locked away when you’re not using it.
Video cameras — Larger motor homes often have video cameras on the back. Couple in a video capture card — internal or USB — and an inexpensive webcam from Logitech and you have the same capability.