AG Neovo manual Peripheral Composition Overview, Output Data, TSC-35/RU User’s Guide

TSC-35/RU User’s Guide

1-3. Peripheral Composition Overview

5 wire resistive touch screen is operated by resistance sensitive system between two layers such as film or glass. Two pieces of transparent materials with conductive coating are placed in the same direction as two electrodes face each other. The 5 wire touch screen is activated when these transparent conductive layers are pressed to contact each other with a finger or a pen. The one of these conductive layers func- tions as an X/Y-coordinates electric circuits and the other as a detection circuits.

To measure the X-coordinates, TSC-35/RU makes two corners Vcc among four corners. And makes oth- ers GND. When the touch screen is pressed under this environment the voltage of the X-coordinates re- sistance is detected by the detection layer (A_in) at the input point (x1), where the X-Y coordinate resis- tance layers make contact. The detected voltage in supply side is higher than the GND side, which means ‘A_in’=Vcc at the point ‘E’ and ‘A_in’=0(*1) at the point ‘A’. TSC-35/RU calculates coordinates data starting from A/D conversion of the ‘A_in’ voltage. The Y-coordinates is measured in the same way. By repeating this process alternately, coordinate value at the input point is determined.

(*1) Excluding the loss in the controller circuits and touch screen. Actual detected voltage should be lower than ‘Vcc - GND’ because of loss happened in the circuitry.

(Detection layer)

A_in

5V (Drive layer)

Vcc = 5.0V

xl	A_in	Output Data
A	0V	0000h (Min.)
B	1.25V	00FFh
C	2.5V	01FFh
D	3.75V	02FFh
E	5V	03FFh (Max.)

E	D	C	B	A
	(Touch Screen)			Touch

xl

Detection layer

Drive layer

Vcc

E D C B A

(TSC-35/RU)

(TSC-30/IC)

A_in

(RS-232C/USB)

To host

Document No. DER-S0019A 3 Rev.1.1 ©2008 DMC Co., Ltd.