Page 279 - Making PIC Microcontroller Instruments and Controllers

BUILDING A SIMPLE EIGHT.BUTTON

TOUCH PANEL

Project 6

TOUCH PA ELS
Today, we see touch panels used everywhere. Every restaurant and store you visit has
a handful oftbem. But how exacdy do they work? WeIl, this chapter describes one way
to skin this cat.
If you design an instrument or confoller that needs a control panel in a hu.ry, by iar
the easiest way to make one is to do it with a touch panel. They are flexible and inex-
pensive and they go together fast. They are easily reprcgrammed and most can be used
with many applications just by changing the software. Depending on your require-
ments, the panel may be able to employ the PIC used by the instrumenrcontroller you
are designing, or it can be designed to have its own dedicated pIC.
In this project, we will build a touch panel to be placed over a plain piece of paper,
with the functions written or the paper (see Figure 20.I ). This panel will contpl the oper
ation of two LEDS connected to the LAB-X I . We will control the opemtion of the LEDS
liom this panel. The following functions will be implemented. (Make a mental note that
the control of a couple of small dc motors would be almost identical to this application.)

I Select the LED to addrcss
r Tum LED on and off
I Select steady on or blinking for each LED
I Blinl slo$er and bltnk fl].ter lor edch LED

The principles involved in creating a touch interface for any number of apptications are
the same. Once you know how to create the interface on the LAB Xl, you will be able
to add the interface to any surface. Though usually placed in front of a CRT, a touch inter-
face is particularly well suited to being placed in front of printed and painted surfaces ro