ScreenCoder

UR7HCTS2-U860

High-Performance USB

Touch Screen Controller / Digitizer

ScreenCoder, MouseCoder are trademarks of
Semtech Corp. All other trademarks belong to
their respective companies.

www.semtech.com

HID & SYSTEM MANAGEMENT PRODUCTS, MOUSECODER

FAMILY

DESCRIPTION

FEATURES

· Handhelds/Notebooks
· Portable Devices

· Interactive Kiosks
· Industrial/Custom Touch Screens

The ScreenCoder

USB IC is the

first single IC that seamlessly
interfaces ANY 4- or 8-wire
resistive touch screen to a USB-
equipped system. It is also the
first touch screen controller IC on
the market designed to
accommodate a very wide range of
size, capacitance and resistance of
4- or 8-wire touch screens,
providing a universal performance
solution among different OEM
products and touch screen
vendors. This unique feature of the
IC provides OEMs with a wide
variety of interchangeable touch
screen options.

Unlike digitizers, the
ScreenCoder

USB integrates a

digitizer with a controller that
performs all touch detection, noise
filtering, error elimination and
provides the host with processed
and stable positioning data over
USB. Semtech's unique motion
algorithms provide high resistance
to RF and other noise sources
resulting in precise, non-jittery
cursor control.

Ideal application for the
ScreenCoder

USB include

portable devices, interactive kiosks
and industrial / custom displays
with integrated touch screens.

The universal features of the
ScreenCoder

USB, as

implemented in both the system
and the sensor interface, reduce
the development effort and cost of
touch input based systems. The
ScreenCoder

USB is available in

a slim, 36-pin SSOP package.

· Highly resistant to RF and other

noise

· No digitizer or external A/D

necessary

· Fully compliant with USB HID

specifications; works with native
USB drivers including Windows®
98, Me and 2000

· Convienent calibration applet

offered free of charge

· Uses slim 36-pin, SSOP package
· Customized versions available

· Controller & digitizer in a single IC
· Interfaces the system via USB
· Works with ANY 4- or 8-wire

resistive touch screen regardless
of size, material or vendor

· Provides high resolution - 1000

points per axis, enabling IC to
make precise drawing and
signature captures

· Accurate, quick touch response

due to Semtech's advanced
sampling technology and
algorithms

RSVD1

RSVD2
RSVD3

SXL

SYT
SYB

SXR

RSVD4

RSVD5

RSVD6

RSVD7

VREF

_RESET

VSS2

VDD

OSCIN

_OSCOUT

VSS

D+

D-

_RB

RSVD13

XR2

YB2
YT2

XL2

RSVD12
RSVD11
USBV
RSVD10
RSVD9
RSVD8
XL1
YT1
YB1
XR1

36-pin SSOP

APPLICATIONS

PIN ASSIGNMENTS

ORDERING CODE

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Package Options

Pitch in mm's

TA=-20° C to +85° C

36-pin, Plastic SSOP

0.8mm

UR7HCTS2-U860-DR

Other Materials

Type

Order number

ScreenCoder

USB Eval Kit

Evaluation Kit

EVK7-TS2-U860-XXX

Power

Management

Section

Power -On Reset

16-Bit Timer

Oscillator Circuit

Sensor Interface

Switch Interface

Touch Panel

Interface

USB

Communication

Interface

CIIN

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BLOCK DIAGRAM FOR THE UR7HCTS2-U860

FUNCTIONAL DESCRIPTION

PIN DEFINITIONS

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Mnemonic

Pin #

Type

Name and Function

Power:
VDD

Power Supply

VSS

14,18

Ground

3.3V

USB Reference Voltage Out

_Reset

Reset

Oscillators:
OSCI

Oscillator Input

OSCO

Oscillator Output

USB:
D-

I/O

USB D- Line

D+

I/O

USB D+ Line

Touch
Screen:
XR1, XR2

19,32

I/O

Touch Screen Right Drive Pins

YB1, YB2

31,20

I/O

Touch Screen Bottom Drive Pins

YT1, YT2

21,30

I/O

Touch Screen Top Drive Pins

XL1, XL2

22,29

I/O

Touch Screen Left Drive Pins

SXR

Touch Screen Sense Pin: for X Right

SYB

Touch Screen Sense Pin: for Y Bottom

SYT

Touch Screen Sense Pin: for Y Top

SXL

Touch Screen Sense Pin: for X Left

VREF

Voltage Reference for A/D Converter

SOUT

Output control data to A/D Converter

_RB

Mouse Right Button

RDVD1-13

1-3,8-11

I/O

Reserved for future use

23-25,

27-28

Note: An underscore before a pin mnemonic denotes an active low signal.
Pin Types Legend: I=Input; O=Output; I/O=Input or Output; P=Power; Al= Analog Input

The UR7HCTS2-U860 consists
functionally of five major sections
(see the Functional Diagram on
Page 2). These are the Sensor
Interface, the Power Management
Section, the 16-Bit Timer, the
Oscillator Circuit and the USB
Interface.

If the system does not allow remote wake-up, the ScreenCoder

USB will

not send resume messages to the system when it is awoken by activity on
the touch screen or button.

This IC has a built-in Oscillator
circuit capable of operations with
an external 6.00 MHz Clock source,
or a Ceramic Resonator (preferably
with built-in Load Capacitors) or a
Crystal with external Load
Capacitors.

OSCILLATOR

According to the USB specification,
if there is no activity of the USB port
for 3 ms, the system is considered
to be in a suspended state. The
ScreenCoder

USB IC, on

detecting that the system is in
suspend, will check the state of the
touch screen and the right button.
If there is no touch pressure
detected or no button pressed, the
ScreenCoder

USB enters into the

suspended state. In suspend the
IC fully complies with the USB
specification for the power
consumption, dissipating current
only in the USB-mandated pull-up
for the device identification.

Another technique the IC uses to
conserve power is called remote
wake-up. If the system relies on the
device to perform wake-up, the IC
will send a resume message to the
system when there is activity on the
touch screen or button.

POWER MANAGEMENT

POWER MANAGEMENT (CON'T)

TOUCH SCREEN SENSOR INTERFACE

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The ScreenCoder

USB can acquire data from any 4- or 8-wire resistive touch screen sensors. The sensor

interface has the following features:

Touch detection

The IC periodically checks touch pressure applied to the panel. If there is no touch, the IC will not perform
measurements and will not send data to system. When touch pressure is detected, the IC further qualifies and
determines the amount of pressure. Semtech's proprietary, patent-pending touch detection algorithm performs this
test very quickly, accommodating sensors with various plate-to-plate capacitances.

Touch Measurement

Position information is only collected if it has been determined that the touch pressure is sufficient for an accurate
reading. To obtain position information from the Resistive Touch Screen Sensor, the ScreenCoder

USB uses four

internal drivers (two pins for each driver) and four sense lines. During sampling, the drivers of the X-axis are
activated by setting one X-drive high and the other X-drive low. The drivers for Y-axis are set floating. This action
produces a voltage gradient across the touch screen's surface in the X direction. The internal A/D measures both
the voltage across the activated X-plane and the voltage potential between the planes. Next, the drivers for the Y-
axis are activated while the drivers for X-axis are set floating. Again, the internal A/D measures both voltage across
the activated plane and potential between the planes. The X and Y absolute position is obtained from these four
A/D measurements. The IC keeps measuring the touch pressure even while the positioning data is acquired. If
insufficient touch pressure is detected during sampling of the position, the current data set will be rejected.

Touch algorithm

Due to vibration and electrical noise, the raw data can not be used directly. Internal data processing delivers
consistent position accuracy and quick touch response.

Resolution

The ScreenCoder

USB uses a built-in A/D converter to get the touch position. The maximum touch screen

resolution is 1000 points per direction. Resolution varies somewhat for different touch screen sensors, due to
voltage droop on connecting wires.

Touch screen from different makers

Operating parameters for the touch screens from different manufacturers vary depending on the size of the sensor,
material it is made from, and mechanical construction. The ScreenCoder

USB takes these properties into

account, and adjusts automatically for plate-to-plate capacitance, intrinsic plate resistances, etc.

Buttons

The ScreenCoder

USB implements both left and right buttons, however, there is no physical left button. Left

button press is reported when there is touch pressure on the panel. The left button is released when there is no
pressure on the panel. The right button is a physical button, and can be used individually.

Offset

Part

Size

Value

Description

Device Descriptor
0

bLength

0x12

Numeric expression specifying the size of
device descriptor

bDescriptonType

0x01

Device descriptor type

bcdUSB

0x0100

USB HID spec release number 01.00

bDeviceClass

0x00

Class code

bDeviceSubClass

0x00

Sub class code

bDeviceProtocol

0x00

Protocol code

bMaxPacketSize0

0x08

Maximum packet size for EP0

idVendor

0x047A

USAR's vendor ID

idProduct

0x0004

USAR ScreenCoder

USB Product ID

bcdDevice

0x0061

Device release number

iManufacture

0x04

Index of string descriptor describing
manufacturer

iProduct

0x0E

Index of string descriptor describing
product

iSerialNumber

0x00

Index of String descriptor describing
serial number

bNum-

0x01

Number of possible configurations

Configuration Descriptor
0

bLength

0x09

Size of configuration descriptor in bytes

bDescriptorType

0x02

Configuration (assigned by USB)

wTotalLength

0x0022

Total length of data returned for this

bNumInterface

0x01

Number of interfaces supported by this
configuration

bConfigurationValue1

0x01

Current configuration value

iConfiguration

0x00

Configuration string descriptor index

bmAttribute

0xA0

Configuration characteristics - bus
powered, with remote wakeup

MaxPower

0x32

Maximum power consumption of USB
device 100 mA

Interface Descriptor
0

bLength

0x09

Size of Interface descriptor in bytes

bDescriptorType

0x04

Interface descriptor type

bInterfaceNumber 1

0x00

Number of interface

bAlternateSetting

0x00

Number of alternate setting

bNumEndpoints

0x01

Number of endpoint

bInterfaceClass

0x03

Class code (HID)

bInterfaceSubClass 1

0x00

Subclass code (nor boot interface
subclass)

bInterfaceProtocol 1

0x02

Protocol code = mouse

iInterface

0x00

Index of string descriptor describing this
interface

HID Descriptor
0

bLength

0x09

Size of HID descriptor in byte

bDescriptorType

0x21

HID descriptor type

bcdHID

0x0100

HID Spec release number

bCountryCode

0x00

Hardware target country

bNumDescriptor

0x01

Number of HID class descriptor follow

bDescriptorType

0x22

Report descriptor type

wDescriptorLength 2

0x0038

Total length of report descriptor

USB FUNCTIONALITY

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The ScreenCoder

USB is a low-

speed USB device with remote
wake-up capability. The IC asks
the system to send report requests
every 10ms according to USB
specification for low speed device.

The ScreenCoder

USB describes

itself as a pointer, and provides
absolute position data to the
system.

USB DESCRIPTORS

USB DESCRIPTORS, (CON'T)

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Offset

Part

Size

Value

Description

Endpoint Descriptor
0

bLength

0x07

Size of endpoint descriptor in bytes

bDescriptorType

0x05

Endpoint descriptor type

bEndpointAddress

0x81

Endpoint address (IN, Endpoint 1)

bmAttribute

0x03

Endpoint's attribute (interrupt)

WMaxPacketSize

0x0005

Maximum packet size

BInterval

0x0A

Interval for polling (poll every 10 ms)

String Descriptor
1

bLength

0x04

Length of string description in bytes

bDescriptorType

0x03

Descriptor type = String

bString

0x0904

LangID code = English

bLength

0x0A

Length of string descriptor

bDescriptorType

0x03

Descriptor Type = String

bString

`U',0,'S', Manufacturer
0,'A',0,
'R',0

bLength

0x3A

Length of string descriptor

bDescriptorType

0x03

Descriptor type = String

bString

`S',0,'c'

"ScreenCoderTM UR7HCTS2-U860"

0,'r',0,
'e',0,etc.

Offset

Data

Mnemonic

Value

Report Descriptor
0

05 01

Usage Page

Generic Desktop

09 01

Usage

Pointer

A1 01

Collection

Application

09 01

Usage

Pointer

A1 00

Collection

Physical

05 09

Usage page

Buttons

19 01

Usage Minimum

29 03

Usage Maximum

15 00

Logical Minimum

25 01

Logical Maximum

95 03

Report Count

75 01

Report Size

81 02

Input

Variable

95 01

Report Count

75 05

Report Size

81 01

Input

Constant

05 01

Usage Page

Generic Desktop

09 30

Usage

09, 31

Usage

15, 00

Logical Maximum

26, FF 7F

Usage Maximum

15 bits 7FFF

35, 00

Physical Minimum

46, FF 7F

Physical Maximum

15 bits 7FFF

75, 10

Report Size

16 bits

95, 02

Report Count

81, 02

Input

Variable

End Collection

SUGGESTED INTERFACING FOR THE SCREENCODER

USB UR7HCTS2-U860-DR

www.semtech.com

Y1 == 6.00 MHz Ceramic Resonator with Built-i

n Load Capacitors.

SHIEL

Mounting h

l
e

NOTES:

See Not

e
s

Connect Drive and Sense lines together for the 4-wire sensor

Crystals can NOT b

e used.

U860 == USB Out, 6.00 MHz, 8/4-wire, Model0

ScreenCoder(TM) USB UR7HCTS2-U860

SYB

SYT

SXL

SXR

GND

VDD

GND

VDD

GND

1.5K

10nF

+/-10% X7R

10nF

+/-10% X7R

10uF

0.1uF

RN1

4.7K

6.00MHz

SW1

RIGHT BUTTON

54VC4502ECB

0.1uF

10nF

+/-10% X7R

10nF

+/-10% X7R

UR7HCTS2-U860

RVSD1

RVSD2

RVSD3

SXL

SYT

SYB

SXR

RVSD4

RVSD5

RVSD6

RVSD7

VREF

RESET

VSS2

VDD

OSCIN

OSCOUT

VSS

D+

D-

RVSD13

XR2

YB2

YT2

XL2

RVSD12

RVSD11

USBV

RVSD10

RVSD9

RVSD8

XL1

YT1

YB1

XR1

DRV_YB

SENSE_YB

SENSE_XL

DRV_XL

SENSE_XR

DRV_XR

DRV_YT

SENSE_YT

36-pin SSOP

ELECTRICAL SPECIFICATIONS

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Absolute Maximum Ratings
Ratings

Symbol

Value

Unit

Supply Voltage

Vdd

-0.3 to 7.0

Input Voltage

Vin

Vss -0.3 to Vdd +0.3

Current Drain per Pin

(not including Vss or Vdd)
Operating Temperature

T low to T high

° C

UR7HCTS2-U860

-20 to +85

° C

Storage Temperature Range

Tstg

-40 to +125

° C

DC Electrical Characteristics, Temperature range=T low to T high unless otherwise noted)
Characteristic

Symbol

Min

Typ

Max

Unit

Supply Voltage

3.0

5.0

5.5

Output Voltage (10

µA load)

Voh

Vdd0.1

Vol

0.1

Input High Voltage

Vih

0.8 x Vdd

Vdd

Input Low Voltage

Vil

Vss

0.2xVdd

Input Current

Iin

+/- 10

µA

Supply Current
(Vdd=5.0 Vdc+/-10%, Vss=0)

Idd

3.0

TBD

Control Timing (Vdd=5.0 Vdc +/-10%, Vss=0 Vdc, Temperature range=T low to T high unless otherwise noted)
Characteristic

Symbol

Min

Typ

Max

Unit

Frequency of Operation

fosc

MHz

Crystal Option

6.0

External Clock Option

6.0

SCREENCODER

USB UR7HCTS2-U860 BILL OF MATERIALS

www.semtech.com

UR7HCTS2-U860-DR BOM
Description

Quantity

Manufacturer

Part#

Description

Capacitors:
C1, C7

Generic

Any

.1uF Capacitor

Generic

Any

10uF Capacitor

C3, C4, C5, C6

Generic

Any

0.01uF Capacitor, 10% X7R or better

Connectors:
J1

Generic

Any

USB Connector

ICs:
U1

USAR

UR7HCTS2-860

ScreenCoder

Controller

TelCom

TC54VC2702ECB

Low-power Reset Voltage Detector

Resistors:
R1, R2

Generic

Any

30 Ohms Resistor

Generic

Any

1.5k Resistor

RN1

Generic

Any

4x, 4.7k Resistor Network

Resonator:
Y1

Panasonic

EFO-S6004E5

6.00MHz Ceramic Resonator, w/ built-in Load Caps

Button:
SW1

Generic

Any

Push Button

Revised 10/03/00

www.semtech.com

For sales information
and product literature,
contact:

HID & System Mgmt Division
Semtech Corporation
568 Broadway
New York, NY 10012
hidinfo@semtech.com
http://www.semtech.com
212 226 2042 Telephone
212 226 3215 Telefax

Semtech Western Regional Sales
805-498-2111 Telephone
805-498-3804 Telefax

Semtech Central Regional Sales
972-437-0380 Telephone
972-437-0381 Telefax

Semtech Eastern Regional Sales
203-964-1766 Telephone
203-964-1755 Telefax

Semtech Asia-Pacific Sales Office
+886-2-2748-3380 Telephone
+886-2-2748-3390 Telefax

Semtech Japan Sales Office
+81-45-948-5925 Telephone
+81-45-948-5930 Telefax

Semtech Korea Sales Sales
+82-2-527-4377 Telephone
+82-2-527-4376 Telefax

Northern European Sales Office
+44 (0)2380-769008 Telephone
+44 (0)2380-768612 Telefax

Southern European Sales Office
+33 (0)1 69-28-22-00 Telephone
+33 (0)1 69-28-12-98 Telefax

Central European Sales Office
+49 (0)8161 140 123 Telephone
+49 (0)8161 140 124 Telefax

Copyright 2000-2001 Semtech Corporation. All rights reserved.
MouseCoder, ScreenCoder and Self-Power Management are
trademarks of Semtech Corporation. Semtech is a registered
trademark of Semtech Company. All other trademarks belong to
their respective companies.

INTELLECTUAL PROPERTY DISCLAIMER
This specification is provided "as is" with no warranties whatsoever
including any warranty of merchantability, fitness for any particular
purpose, or any warranty otherwise arising out of any proposal,
specification or sample. A license is hereby granted to reproduce
and distribute this specification for internal use only. No other
license, expressed or implied to any other intellectual property
rights is granted or intended hereby. Authors of this specification
disclaim any liability, including liability for infringement of proprietary
rights, relating to the implementation of information in this
specification. Authors of this specification also do not warrant or
represent that such implementation(s) will not infringe such rights.

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