© 2009 Microchip Technology, Inc.

DS41393A-Page iii

TABLE OF CONTENTS

1

GENERAL.............................................................................................................................................. 1

2

FEATURES............................................................................................................................................ 1

3

APPLICATIONS..................................................................................................................................... 2

4

ORDERING............................................................................................................................................ 2

5

BLOCK DIAGRAM ................................................................................................................................. 2

6

PIN DIAGRAM ....................................................................................................................................... 3

7

FUNCTIONAL DESCRIPTION .............................................................................................................. 4

7.1

MAIN SCHEMATIC..............................................................................................................................................4

7.2

BILL OF MATERIALS ...........................................................................................................................................4

7.3

4, 5, 8-WIRE SENSOR SELECTION ......................................................................................................................5

7.4

4-WIRE TOUCH SENSOR INTERFACE....................................................................................................................5

7.5

5-WIRE TOUCH SENSOR INTERFACE....................................................................................................................6

7.6

8-WIRE TOUCH SENSOR INTERFACE....................................................................................................................7

7.7

COMMUNICATION INTERFACE..............................................................................................................................8

7.7.1

I

2C............................................................................................................................................8

7.7.2

SPI........................................................................................................................................... 9

7.7.3

UART..................................................................................................................................... 10

7.8

STATUS LED..................................................................................................................................................10

7.9

ESD CONSIDERATIONS ...................................................................................................................................11

7.10

NOISE CONSIDERATIONS .................................................................................................................................11

7.11

TOUCH REPORTING PROTOCOL ........................................................................................................................11

7.12

CONFIGURATION REGISTERS............................................................................................................................12

7.12.1

TouchThreshold Register (offset 0x02)................................................................................. 12

7.12.2

SensitivityFilter Register (offset 0x03)................................................................................... 12

7.12.3

SamplingFast Register (offset 0x04)..................................................................................... 13

7.12.4

SamplingSlow Register (offset 0x05) .................................................................................... 13

7.12.5

AccuracyFilterFast Register (offset 0x06) ............................................................................. 13

7.12.6

AccuracyFilterSlow Register (offset 0x07) ............................................................................ 13

7.12.7

SpeedThreshold Register (offset 0x08) ................................................................................ 13

7.12.8

SleepDelay Register (offset 0x0A) ........................................................................................ 14

7.12.9

PenUpDelay Register (offset 0x0B) ...................................................................................... 14

7.12.10

TouchMode Register (offset 0x0C).................................................................................... 15

7.12.11

TouchOptions Register (offset 0x0D) ................................................................................ 16

7.12.12

CalibrationInset Register (offset 0x0E).............................................................................. 16

7.12.13

PenStateReportDelay Register (offset 0x0F) .................................................................... 17

7.12.14

TouchReportDelay Register (offset 0x11) ......................................................................... 17

7.12.15

User Configuration – Spiking ............................................................................................. 17

7.13

COMMAND FORMAT.........................................................................................................................................17

7.14

COMMAND RESPONSE .....................................................................................................................................18

7.15

COMMANDS ....................................................................................................................................................18

7.15.1

Enable Touch - 0x12 .............................................................................................................18

7.15.2

Disable Touch - 0x13 ............................................................................................................18

7.15.3

Calibrate - 0x14 ..................................................................................................................... 19

7.15.3.1

How the Calibration Data is Encoded and Stored in EEPROM ..................................... 20

7.15.4

Register Read - 0x20 ............................................................................................................21

7.15.5

Register Write - 0x21............................................................................................................. 21

7.15.6

Register Start Address Request - 0x22................................................................................. 21

7.15.7

Registers Write to EEPROM - 0x23 ...................................................................................... 21

7.15.8

EEPROM Read - 0x28 .......................................................................................................... 22

7.15.9

EEPROM Write - 0x29 .......................................................................................................... 22

7.15.10

EEPROM Write to Registers - 0x2B .................................................................................. 22

7.16

CALIBRATION OF TOUCH SENSOR WITH CONTROLLER .........................................................................................23