Document
ScreenCoderTM UR7HCTS2-P840 High-Performance, Low Power PS/2 Touch Screen Controller/Digitizer
HID & SYSTEM MANAGEMENT PRODUCTS, MOUSECODERTM FAMILY DESCRIPTION The ScreenCoderTM PS2 is a highperformance IC that interfaces any 4 or 8-wire resistive touch screen to the standard PS/2 mouse port. Low-power and tiny, the single IC is ideal for portable systems, web phones and interactive kiosks. It offers an advanced algorithm for enhanced motion control as well as an extra port for hot-plug connection of an external PS/2 pointing device. Both the touch screen and the external device can be operated concurrently without any penalty. The UR7HCTS2-P840 is equipped with a special command protocol that enables the touch screen to operate in either relative (mouselike) or absolute positioning mode. Because the IC interfaces via the PS/2 mouse port, it can utilize any standard mouse driver when operating in relative mode. For absolute positioning, offers a highfunctionality driver which includes inking capabilities. Mice connected to the ScreenCoderTM PS2 external mouse port will always act in relative mode, even if the touch screen is operating in the absolute mode. The PS/2 communication channel is bi-directional at 10 kbps.
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FEATURES • Controller & digitizer in a single IC; no need for external A/D • Interfaces ANY 4- or 8-wire resistive touch screen to standard PS/2 mouse port; regardless of size, material or vendor • High-performance IC offers accurate cursor control due to advanced algorithms • Low-power consumption, due to sophisticated power management states, ideal for battery-operated systems • Highly resistant to RF & other noise sources • Enables hot-plug connection of an external pointing device • Wheelmouse functionality is supported in the external pointing device • Other interfaces available • Embedded touch screen and external pointing device can operate concurrently with no performance penalty • Supports both absolute and relative (mouse-like) modes of operation • For relative mode, no special drivers are needed; highfunctionality driver available for absolute mode • Supports all commands defined in the IBM PS/2 Mouse Communication Protocol, as well as Semtech’s extended PS/2 communication protocol with absolute positioning support • Available in a low-profile 32-pin LQFP package • Few external components required
APPLICATIONS • Portable systems • Notebooks and Laptops PIN ASSIGNMENTS
RB RSVD2 RSVD3 RSVD4 RSVD5 POWER_DOWN SXL SYT
32 25 24
• Interactive Kiosks • Touch-enabled monitors
The ScreenCoder PS2 offers builtin A/D. Touch detection and motion are handled in firmware, and no digitizer is required. The cost-effective solution requires few external components, allowing for a simple and real estate saving implementation.
TM
SYB SXR XPWRS RSVD1 VREF RESET VSS2 VDD
8 9 16 17
LB XR2 YB2 YT2 XL2 HDAT XDAT XCLK
ScreenCoder and MouseCoder are trademarks of Semtech Corporation. All other trademarks belong to their respective companies.
Copyright ©1999-2001 Semtech Corporation DOC7-TS2-P840-DS-106
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OCSIN OSCOUT VSS XR1 YB1 YT1 XL1 HCLK
www.semtech.com
ORDERING CODE
Package Options 32-pin, Plastic LQFP Pitch in mm’s 0.5 TA=-20° C to +85° C UR7HCTS2-P840-FG
Other Materials ScreenCoderTM PS2 Eval. Kit
Type Evaluation Kit
Order number EVK7-TS2-P840-XXX
Note 1: XXX= Denotes Revision number
BLOCK DIAGRAM
Left Button
Right Button
PWR_DOWN Power Management XPWRS Switch Interface
HCLK PS/2 Communication Port HDAT
X Input
4
Drivers for Touch Screen Sensor
Y Input
Sense Lines
4
XCLK 8042 Emulation Port XDAT
Control
Sensor Interface
16 bit Timer Power-On Reset Oscillator Circuit
OSCIN
OSCOUT
Copyright ©1999-2001 Semtech Corporation DOC7-TS2-P840-DS-106
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www.semtech.com
PIN DEFINITIONS
Mnemonic VDD VSS VSS2 OSCIN Pin # 8 11 7 9 Type P P P I Name and Function Power Supply Ground Ground Oscillator Input: external clock input or one side of the Ceramic Resonator with built-in Load Capacitors Oscillator Output: open for external clock input or other side of the Ceramic Resonator with built-in Load Capacitors Reset: apply 0V to provide orderly start-up Mouse Data: connects to Host’s data line Mouse Clock: connects to Host’s clock line External Mouse Clock: PS/2 clock signal from external mouse; keep open if unused External Mouse Data: PS/2 data signal from external mouse; keep open if unused Left Button: active low, strobed sampling Right Button: active low, strobed sampling Sensor’s Excitation Driver: connect to X Right Sensor’s Excitation Driver: connect to Y Bottom Sensor’s Excitation Driver: connect to Y Top Sensor’s Excitation Driver: connect to X Left Sensor’s Excitation Driver: connect to X Left Sensor’s Excitation Driver: connect to Y Top Sensor’s Excitation Driver: connect to Y Bottom Sensor’s Excitation Driver: connect to X Right Reference Voltage for built-in A/D Sense line: for X Left Sense line: for Y Top Sense line: for Y Bottom Sense line: for X Right Hardware Power Do.