
TSC2100
SLAS378 NOVEMBER 2003
www.ti.com
15
OVERVIEW
The TSC2100 is a highly integrated touch screen controller with stereo audio codec for portable computing,
communication,
and
entertainment
applications.
A
register-based
architecture
eases
integration
with
microprocessor-based systems through a standard SPI bus. All peripheral functions are controlled through the registers
and onboard state machines.
The TSC2100 consists of the following blocks (refer to the block diagram):
D Touch Screen Interface
D Battery Monitors
D Auxiliary Inputs
D Temperature Monitor
D Audio Codec
Communication to the TSC2100 is via a standard SPI serial interface. This interface requires that the slave select signal
be driven low to communicate with the TSC2100. Data is then shifted into or out of the TSC2100 under control of the host
microprocessor, which also provides the serial data clock.
Control of the TSC2100 and its functions is accomplished by writing to different registers in the TSC2100. A simple
command protocol is used to address the 16bit registers. Registers control the operation of the A/D converter and audio
codec.
A typical application of the TSC2100 is shown in
Figure 14.V1: Main Battery
V2: Secondary Battery
C1: 1 F 10 F (Optional)
C2: 0.1 F
C3, C4: 0.1 mF,
R1, R2: 200 300 W
C1
Touch Screen
Audio
R1
R2
Auxilary Input
AUX
X+
Y+
X
Y
MICBIAS
MICIN
HPR
HPL
VGND
VBAT1
VBAT2
VREF
MCLK
ADWS/
PWDZ
DOUT
LRCK
DIN
BCLK
PINTDAV
MISO
MOSI
SS
SCLK
8 W
Speaker
C3
C4
V1
V2
C2
12S Interface
Master Clock Input
ADC Word Select
Serial Output to CPU/DSP
DAC Word Select
Serial Input From CPU/DSP
Serial Clock Input
SPI Interface
Pen Interrupt Request to CPU
Serial Output to SPI Master
Serial Input From SPI Master
SPI Slave Select Input
SPI Serial Clock Input
2.2 kW
Figure 14. Typical Circuit Configuration
OPERATION—TOUCH SCREEN
A resistive touch screen works by applying a voltage across a resistor network and measuring the change in resistance
at a given point on the matrix where a screen is touched by an input stylus, pen, or finger. The change in the resistance
ratio marks the location on the touch screen.
The TSC2100 supports the resistive 4-wire configurations (see
Figure 14). The circuit determines location in two coordinate
pair dimensions, although a third dimension can be added for measuring pressure.
The 4-Wire Touch Screen Coordinate Pair Measurement
A 4-wire touch screen is constructed as shown in
Figure 15. It consists of two transparent resistive layers separated by
insulating spacers.