Touchscreen basics

[bwhiten]

To eliminate a costly custom front panel with membrane switches I am thinking of using a touchscreen LCD on this pic project. I have written code to scan a keypad before so that is not a concern. My question is: this particular display calls out a "4-wire analog" touchscreen with active regions of top, bottom, left and right. Does this give me 4 possible "touch zones" to place "graphical buttons" in for the user or am I missing something?
Thanks.

[SET]

It sounds like a resistive screen, where the x-position is one pair of wires and the y is the other. Normally you would use a touch controller IC to translate the x/y resistance changes into digital form. No reason why you couldn't use the PIC ADC to do this instead.

[libor]

No.
The '4-wire analog' only describes the interface, it has nothing to do with the resolution of the screen.
There are touch screen controllers with '4-wire analog' input up to a theoretical 4096 x 4096 resolution and you can also have the touch pressure value. Like this here: Touchkit. Actual resolution depends on your fingertip's diameter
There are also stand-alone controller ICs for this with a SPI bus and some fancy addtional functions like battery monitoring, temperature, etc. for 2-3 USD. Like this.

You can easily write your own program in a PIC using the built-in ADCs.
Some info about the various (4-wire, 5 wire and 8 wire) resistive touchscreens' theory of operation you can find here

[bwhiten]

Thanks for the help. The links explain it well. More complicated than I had thought but not impossible.