@cheong: Well I'm trying to make a compact "control panel" similar to what you see here. That unit is typical of what size I need and it is rougly 6" x 8 "in size and about 2" thick. It needs to be mounted inside an electrical box. It will be tough to do that with any kind of notebook/netbook, and on top of that the notebook/netbook won't have a touch screen. Also keep in mind I would need to mount the IO controller in there as well, including the two additional larger relays to drive the two motors.
I'm seeing a re-purposed GPS as having the following advantages:
- Extremely compact considering the hardware it contains.
- No need to assemble anything. Building anything from scratch is going to take a long time, bulky, kludgy, expensive and cheap-looking.
- Already has a high-def, bright display (a requirement for a car GPS).
- Has a built-in backup battery. Something that would have added quite a bit to the cost if building something from scratch.
- The cheap GPSes you find on eBay are cheaper than any combination of hardware I can put together with similar functionality (if that is even possible, which I doubt).
The only downside I can think of is the reliability of the unit. These GPS units are cheap and I'm not sure how they would hold up when installed inside a metal box that sits in the sun all day. Will the battery explode after 3 months? You'd think they will be somewhat hardened considering they need to sit on dashboards inside cars that also sit in the sun all day.
Could there be other downsides? I guess ordering one of these and just trying it out can't hurt.