Datasheet
Circuit Description
3-8
3.3.6 Touch Screen Connectors
A 4-wire touch screen connects to the EVM board through connector J3. This
connector is standard on 3M Touch Systems (formerly MicroTouch) TouchTek
4 touch screens. A standard terminal block connection is available on J1 for
those users who have touch screen connectors that do not match the J3
configuration.
Table 3−10.Touch Screen Input
Reference
Designator
Description
Pin
Number
Signal
Name
Function
1 X− Touch screen X− electrode
2 Y+ Touch screen Y+ electrode
J3, J1 Touch screen input
3 X+ Touch screen X+ electrode
4 Y− Touch screen Y− electrode
3.3.7 Analog Input Connector
The auxiliary and battery inputs to the touch screen controller are brought onto
the EVM board through terminal block J4. The pinout is shown in Table 3− 11.
Table 3−11.Analog Input Connector
Reference
Designator
Description
Pin
Number
Signal
Name
Function
1 VBAT Battery input, 0 V to 6 V
Battery and auxiliary inputs
2 AUX1 Auxiliary input 1, 0 V to VREF
J4
Battery and auxiliary inputs
to the touch screen control
3 AUX2 Auxiliary input 2, 0 V to VREF
4 GND Ground
3.4 Circuit Description
The TSC2101 evaluation kit circuitry consists of a USB microprocessor, power
supply circuitry, touch screen and analog input interfaces, and audio interface
circuitry (both analog and digital). These circuits are described in the following
sections.
3.4.1 USB Microprocessor
The TSC2101EVM has a USB interface for connecting to a PC. This
connection is made through a TAS1020B streaming audio processor, U10.
The SPI interface to the TSC2101 can be controlled from two sources: the
external SPI header, J14, or through the onboard microprocessor (U10) via
USB. The U10 outputs are enabled only when the supplied firmware is loaded,
and the corresponding bus(es) is enabled, refer to switch description for SW2
in section 3.1.
The firmware resides in the serial EEPROM chip, U2. U10 only loads firmware
from U2 when the U2 A1 address line is pulled low. To disable firmware
loading, A1 must be high, by having JM5 removed. Refer to section 3.2.4.