Datasheet CAP1298 Datasheet

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Page 1

8-Channel Capacitive Touch Sensor with

SMBus

Protocol

SMCLK SMDATA

VDD GND

ALERT#

Capacitive Touch Sensing Algorithm

CS1CS2CS3CS4CS6CS7 CS8

CS5 /

Proximity Detection & Signal Guard

CAP1298

PRODUCT FEATURES

General Description

The CAP1298 which incorporates RightTouch® technology, is a multiple channel capacitive touch sensor. It contains eight (8) individual capacitive touch sensor inputs with programmable sensitivity for use in touch sensor applications. Each sensor input is calibrated to compensate for system parasitic capacitance and automatically recalibrated to compensate for gradual environmental changes.

In addition, the CAP1298 can be configured to detect proximity on one or more channels with an optional signal guard to reduce noise sensitivity and to isolate the proximity antenna from nearby conductive surfaces that would otherwise attenuate the e-field.

The CAP1298 includes Multiple Pattern Touch recognition that allows the user to select a specific set of buttons to be touched simultaneously. If this pattern is detected, a status bit is set and an interrupt is generated.

The CAP1298 has Active and Standby states, each with its own sensor input configuration controls. The Combo state allows a combination of sensor input controls to be used which enables one or more sensor inputs to operate as buttons while another sensor input is operating as a proximity detector. Power consumption in the Standby and Combo states is dependent on the number of sensor inputs enabled as well as averaging, sampling time, and cycle time. Deep Sleep is the lowest power state available, drawing 5µA (typical) of current. In this state, no sensor inputs are active, and communications will wake the device.

Datasheet

Applications

 Desktop and Notebook PCs  LCD Monitors  Consumer Electronics  Appliances

Features

 Eight (8) Capacitive Touch Sensor Inputs

— Programmable sensitivity — Automatic recalibration — Calibrates for parasitic capacitance — Individual thresholds for each button

 Proximity Detection  Signal Guard

— Isolates the proximity antenna from attenuation — Reduces system noise sensitivity effects on inputs

 Mu ltiple Button Pattern Detection  Power Button Support  Press and Hold Feature for Volume-like Applications  3.3V or 5V Supply  Analog Filtering for System Noise Sources  RF Detection and Avoidance Filters  Digital EMI Blocker  8kV ESD Rating on All Pins (HBM)  Low Power Operation

— 5µA quiescent current in Deep Sleep — 50µA quiescent current in Standby (1 sensor input

monitored)

— Samples one or more channels in Standby

 SMBus / I  Available in a 16-pin 3mm x 3mm QFN RoHS compliant

package

C Compliant Communication Interface

Block Diagram

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Ordering Information:

ORDERING

NUMBER PACKAGE FEATURES

Datasheet

CAP1298-1-A4-TR 16-pin QFN 3mm x 3mm

(RoHS compliant)

Reel size is 4,000 pieces for 16-Pin QFN

This product meets the halogen maximum concentration values per IEC 61249-2-21

Eight capacitive touch sensor inputs, SMBus interface, SMBus address 0101_000(r/w). Proximity and signal guard.

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Datasheet

Table of Contents

Chapter 1 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Chapter 2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Chapter 3 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1 Communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2 System Management Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.1 SMBus Start Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.2 SMBus Address and RD / WR

3.2.3 SMBus Data Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.4 SMBus ACK and NACK Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.5 SMBus Stop Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2.6 SMBus Timeout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2.7 SMBus and I

3.3 SMBus Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.3.1 SMBus Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3.2 SMBus Read Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3.3 SMBus Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3.4 SMBus Receive Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.4 I

C Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.4.1 Block Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.4.2 Block Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Chapter 4 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.1 Power States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.2 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.3 Capacitive Touch Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.3.1 Capacitive Touch Sensing Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.3.1.1 Active State Sensing Settings........................................................................................20

4.3.1.2 Standby State Sensing Settings ... .... ... ... ... .... ... ... .......................................... ................21

4.3.1.3 Combo State Sensing Settings......................................................................................21

4.3.2 Sensing Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.4 Sensor Input Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.4.1 Automatic Recalibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.4.2 Negative Delta Count Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.4.3 Delayed Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.5 Proximity Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.5.1 Signal Guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.6 Power Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.7 Multiple Touch Pattern Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.8 Noise Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.8.1 Low Frequency Noise Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.8.2 RF Noise Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.8.3 Noise Status and Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.9 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.9.1 ALERT# Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.9.2 Capacitive Sensor Input Interrupt Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.9.3 Interrupts for the Power Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.9.4 Interrupts for Multiple Touch Pattern Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.9.5 Interrupts for Sensor Input Calibration Failures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.9.6 Interrupts for Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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Datasheet

Chapter 5 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

5.1 Main Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

5.2 Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.2.1 General Status - 02h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.2.2 Sensor Input Status - 03h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5.3 Noise Flag Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5.4 Sensor Input Delta Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.5 Sensitivity Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

5.6 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.6.1 Configuration - 20h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.6.2 Configuration 2 - 44h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.7 Sensor Input Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.8 Sensor Input Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.9 Sensor Input Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5.10 Averaging and Sampling Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5.11 Calibration Activate and Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

5.12 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.13 Repeat Rate Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.14 Signal Guard Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

5.15 Multiple Touch Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

5.16 Multiple Touch Pattern Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

5.17 Multiple Touch Pattern Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

5.18 Base Count Out of Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

5.19 Recalibration Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

5.20 Sensor Input Threshold Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

5.21 Sensor Input Noise Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

5.22 Standby Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

5.23 Standby Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

5.24 Standby Sensitivity Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

5.25 Standby Threshold Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

5.26 Sensor Input Base Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

5.27 Power Button Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

5.28 Power Button Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

5.29 Sensor Input Calibration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

5.30 Calibration Sensitivity Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

5.31 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

5.32 Manufacturer ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

5.33 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Chapter 6 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

6.1 CAP1298 Package Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

6.2 Package Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Appendix ADevice Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

A.1 Delta from CAP1128 / CAP1188 to CAP1298 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

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Datasheet

List of Figures

Figure 1.1 CAP1298-1 Pin Diagram (16-Pin QFN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 3.1 SMBus Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 4.1 System Diagram for CAP1298 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 4.2 POR and PORR With Slow Rising V

Figure 4.3 Signal Guard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 4.4 Sensor Interrupt Behavior - Repeat Rate Enabled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 4.5 Sensor Interrupt Behavior - No Repeat Rate Enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 6.1 CAP1298 Package Drawing - 16-Pin QFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Figure 6.2 CAP1298 Package Dimensions - 16-Pin QFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . 63

Figure 6.3 CAP1298 PCB Land Pattern and Stencil - 16-Pin QFN 3mm x 3mm . . . . . . . . . . . . . . . . 64

Figure 6.4 CAP1298-1 Package Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

and BOR with Falling V

DD . . . . . . . . . . . . . . . . . . . . . . . 20

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Datasheet

List of Tables

Table 1.1 Pin Description for CAP1298 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Table 1.2 Pin Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 2.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 2.2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 3.1 Protocol Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table 3.2 Write Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 3.3 Read Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 3.4 Send Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 3.5 Receive Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 3.6 Block Read Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 3.7 Block Write Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Table 4.1 Ideal Base Counts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 5.1 Register Set in Hexadecimal Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 5.2 Main Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Table 5.3 Power State Bit Overrides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Table 5.4 GAIN and C_GAIN Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Table 5.5 Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Table 5.6 Noise Flag Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Table 5.7 Sensor Input Delta Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Table 5.8 Sensitivity Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table 5.9 DELTA_SENSE Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table 5.10 BASE_SHIFT Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Table 5.11 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Table 5.12 Sensor Input Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Table 5.13 Sensor Input Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Table 5.14 MAX_DUR Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Table 5.15 RPT_RATE Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Table 5.16 Sensor Input Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Table 5.17 M_PRESS Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Table 5.18 Averaging and Sampling Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Table 5.19 AVG Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table 5.20 SAMP_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table 5.21 CYCLE_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table 5.22 Calibration Activate and Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table 5.23 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table 5.24 Repeat Rate Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table 5.25 Signal Guard Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Table 5.26 Multiple Touch Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 5.27 B_MULT_T Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 5.28 Multiple Touch Pattern Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 5.29 MTP_TH Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Table 5.30 Multiple Touch Pattern Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 5.31 Base Count Out of Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Table 5.32 Recalibration Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Table 5.33 NEG_DELTA_CNT Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Table 5.34 CAL_CFG Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Table 5.35 Sensor Input Threshold Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Table 5.36 Sensor Input Noise Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Table 5.37 CSx_BN_TH Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Table 5.38 Standby Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Table 5.39 Standby Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Table 5.40 STBY_AVG Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Table 5.41 STBY_SAMP_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 5.42 STBY_CY_TIME Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 5.43 Standby Sensitivity Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 5.44 STBY_SENSE Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Table 5.45 Standby Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Table 5.46 Sensor Input Base Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Table 5.47 Power Button Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Table 5.48 PWR_BTN Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Table 5.49 Power Button Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Table 5.50 Power Button Time Bits Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Table 5.51 Sensor Input Calibration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Table 5.52 Calibration Sensitivity Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Table 5.53 CALSENX Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Table 5.54 Product ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Table 5.55 Vendor ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Table 5.56 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Table A.1 Register Delta. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Table 6.1 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

1 2 3 4

12 11 10

VDD

SMCLK

SMDATA

CS7

GND

CS5 / SG CS6

CS1

CS2

CS4

CS8

CS3

GND

N/C

Exposed pad

ALERT#

Chapter 1 Pin Description

Datasheet

Figure 1.1 CAP1298-1 Pin Diagram (16-Pin QFN)

Table 1.1 Pin Description for CAP1298

NUMBER PIN NAME PIN FUNCTION PIN TYPE

1ALERT#

2SMDATA

3SMCLK

4 VDD Positive Power supply Power n/a

5 N/C Not internally connected n/a

6 N/C Not internally connected n/a

7 GND Ground Power n/a 8 GND Ground Power n/a

ALERT# - Active low alert / interrupt output for SMBus

SMDATA - Bi-directional, open-drain SMBus or I

- requires pull-up resistor

SMCLK - SMBus or I

alert

C clock input - requires pull-up

resistor

C data

DIOD n/a

DI n/a

UNUSED

CONNECTION

Connect to

Ground

Connect to

Ground

Connect to

Ground

9 CS8 Capacitive Touch Sensor Input 8 AIO

10 CS7 Capacitive Touch Sensor Input 7 AIO

DS01571A-page 8  2013 Microchip Technology Inc.

Connect to

Ground

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Table 1.1 Pin Description for CAP1298 (continued)

NUMBER PIN NAME PIN FUNCTION PIN TYPE

11 CS6 Capacitive Touch Sensor Input 6 AIO

CS5 - Capacitive Touch Sensor Input 5 AIO

12 CS5 / SG

UNUSED

CONNECTION

Connect to

Ground

Connect to

Ground

SG - Signal Guard Output AIO Leave Open

13 CS4 Capacitive Touch Sensor Input 4 AIO

14 CS3 Capacitive Touch Sensor Input 3 AIO

15 CS2 Capacitive Touch Sensor Input 2 AIO

16 CS1 Capacitive Touch Sensor Input 1 AIO

Connect to

Ground

Connect to

Ground

Connect to

Ground

Connect to

Ground

Bottom pad Exposed pad Not internally connected, but recommend grounding - -

APPLICATION NOTE: All digital pins are 5V tolerant pins.

The pin types are described in Table1.2.

Table 1.2 Pin Types

PIN TYPE DESCRIPTION

Power This pin is used to supply power or ground to th e device.

DI Digital Input - This pin is used as a digital input. This pin is 5V tolerant.

AIO Analog Input / Output - This pin is used as an I/O for analog signals.

DIOD

Digital Input / Open Drain Output - This pin is used as a digital I/O. When it is used as an output, it is open drain and requires a pull-up resistor. This pin is 5V tolerant.

Open Drain Digital Output - This pin is used as a digital output. It is open drain and requires a pull-up resistor. This pin is 5V tolerant.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Chapter 2 Electrical Specifications

Table 2.1 Absolute Maximum Ratings

Voltage on VDD pin -0.3 to 6.5 V Voltage on CS pins to GND -0.3 to 4.0 V

Datasheet

Voltage on 5V tolerant pins (V Voltage on 5V tolerant pins (|V Input current to any pin except VDD +

) -0.3 to 5.5 V

5VT_PIN

- VDD|) (see Note 2.2)0 to 3.6 V

5VT_PIN

10 mA Output short circuit current Continuous N/A Package Power Dissipation up to TA = 85°C for 16-pin QFN

0.5 W

(see Note 2.3) Junction to Ambient (θ

) (see Note 2.4)70 °C/W

Operating Ambient Temperature Range -40 to 125 °C Storage Temperature Range -55 to 150 °C ESD Rating, All Pins, HBM 8000 V

Note 2.1 Stresses above those listed could cause permanent damage to the device. This is a stress

rating only and functional operation of the device at any other condition above those indicated in the operation sections of this specification is not implied.

Note 2.2 For the 5V tolerant pins that have a pull-up resistor, the voltage difference between

and VDD must never exceed 3.6V.

5VT_PIN

Note 2.3 The Package Power Dissipation specification assumes a recommended thermal via design

consisting of a 2x2 matrix of 0.3mm (12mil) vias at 1.0mm pitch conn ected to the ground plane with a 1.6 x 1.6mm thermal landing.

Note 2.4 Junction to Ambient (θ

) is dependent on the design of the thermal vias. Without thermal

vias and a thermal landing, the θJA will be higher.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Table 2.2 Electrical Specifications

VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.

CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS

DC POWER

Supply Voltage V

Supply Current

Maximum Base

Capacitance

Minimum Detectable

Capacitive Shift

STBY_DEF

STBY_LP

DSLEEP_3V

DSLEEP_5V

BASE

ΔC

TOUCH

3.0 5.5 V Standby state active

120 170 µA

1 sensor input monitored

Default conditions (8 avg, 70ms

cycle time)

Standby state active

50 µA

1 sensor input monitored

1 avg, 140ms cycle time

Deep Sleep state active

5TBDµA

No communications

< 40°C

3.135 < V

< 3.465V

Deep Sleep state active

TBD TBD µA

500 750 µA

No communications

< 40°C

= 5V

Capacitive Sensing Active

signal guard disabled

CAPACITIVE TOUCH SENSOR INPUTS

50 pF Pad un touched

20 fF Pad touched - defaul t conditions

Recommended Cap

Shift

ΔC

TOUCH

0.1 2 pF Pad touched - Not tested

Untouched Current Counts

Power Supply

Rejection

PSR ±3 ±10

counts

/ V

Base Capacitance 5pF - 50pF

Negative Delta Counts disabled

Maximum sensitivity

All other parameters default

POWER-ON AND BROWN-OUT RESET (SEE Section 4.2, "Reset")

Power-On Reset

Voltage

Power-On Reset Release Voltage

Brown-Out Reset V

PORR

POR

BOR

1 1.3 V Pin States Defined

2.85 V

Rising V

Ensured by design

2.8 V Falling V

VDD Rise Rate

(ensures internal

POR signal)

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0.05 V/ms 0 to 3V in 60ms

Page 12

8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Table 2.2 Electrical Specifications (continued)

= 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.

CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS

Datasheet

Power-Up Timer

Period

Brown-Out Reset

Voltage Delay

BORDC

Time to

Communications

Ready

Time to First

Conversion Ready

COMM_DLY

CONV_DLY

Output Low Voltage V

Output High Voltage V

Input High Voltage V

Input Low Voltage V

Leakage Current I

PWRT

LEAK

10 ms

1µsV

= V

BOR

- 1

TIMING

15 ms

170 200 ms

I/O PINS

VDD -

0.4

0.4 V I

SOURCE_IO

SINK_IO

= 8mA

2.0 V

0.8 V powered or unpowered

< 85°C

±5 µA

pull-up voltage <

3.6V if

unpowered

SG PIN

Capacitive Drive

Capability

BASE_SG

20 20 0 pF capacitance to ground

SMBUS TIMING

Input Capacitance C

Clock Frequency f

Spike Suppression t

Bus Free Time Stop

to Start

Start Setup Time t

Sta rt Ho ld Ti me t

Stop Setup Time t

Data Hold Time t Data Hold Time t

Data Setup Time t

DS01571A-page 12  2013 Microchip Technology Inc.

SMB

BUF

SU:STA

HD:STA

SU:STO

HD:DAT

SU:DAT

10 400 kHz

1.3 µs

0.6 µs

0.6 µs 0 µs W hen transmitting to the master

0.3 µs When receiving from the master

0.6 µs

5pF

50 ns

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Table 2.2 Electrical Specifications (continued)

VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.

CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS

Clock Low Period t

Clock High Period t

Clock / Data Fall

Time

Clock / Data Rise

Time

Capacitive Load C

LOW

HIGH

FALL

RISE

LOAD

1.3 µs

0.6 µs

300 ns Min = 20+0.1C

400 pF per bus line

LOAD

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

SMDATA

SMCLK

BUF

S - Start Condition

P - Stop Condition

HIGH

LOW

HD:STA

SU:STO

HD:STA

HD:DAT

SU:DAT

SU:STA

FALL

RISE

Chapter 3 Communications

3.1 Communications

The CAP1298 communicates using the SMBus or I2C protocol.

3.2 System Management Bus

The CAP1298 communicates with a host controller, such as an MCHP SIO, through the SMBus. The SMBus is a two-wire serial communication protocol between a computer host and its peripheral devices. A detailed timing diagram is shown in Figure 3.1. Stretching of the SMCLK signal is supported; however, the CAP1298 will not stretch the clock signal.

Datasheet

Figure 3.1 SMBus Timing Diagram

3.2.1 SMBus Start Bit

The SMBus Start bit is defined as a transition of the SMBus Data line from a logic ‘1’ state to a logic ‘0’ state while the SMBus Clock line is in a logic ‘1’ state.

3.2.2 SMBus Address and RD / WR Bit

The SMBus Address Byte consists of the 7-bit client address followed by the RD / WR indicator bit. If this RD / WR bit is a logic ‘0’, then the SMBus Host is writing data to the client device. If this RD / WR bit is a logic ‘1’, then the SMBus Host is reading data from the client device.

The CAP1298 responds to SMBus address 0101_000(r/w).

3.2.3 SMBus Data Bytes

All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.

3.2.4 SMBus ACK and NACK Bits

The SMBus client will acknowledge all data bytes that it receives. This is done by the cl ient device

DS01571A-page 14  2013 Microchip Technology Inc.

pulling the SMBus Data line low after the 8th bit of each byte that is transmitted. This applies to both the Write Byte and Block Write protocols.

The Host will NACK (not acknowledge) the last data byte to be received from the client by holding the SMBus data line high after the 8th data bit has been sent. For the Block Read protocol, the Host will ACK each data byte that it receives except the last data byte.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

3.2.5 SMBus Stop Bit

The SMBus Stop bit is defined as a transition of the SMBus Data line from a logic ‘0’ state to a logic ‘1’ state while the SMBus clock line is in a logic ‘1’ state. When the CAP1298 detects an SMBus Stop bit and it has been communicating with the SMBus protocol, it will reset its client interface and prepare to receive further communications.

3.2.6 SMBus Timeout

The CAP1298 includes an SMBus timeout feature. Following a 30ms period of inactivity on the SMBus where the SMCLK pin is held low, the device will timeout and reset the SMBus interface.

The timeout function defaults to disabled. It can be enabled by setting the TIMEOUT bit in the Configuration register (see Section 5.6, "Configuration Registers").

3.2.7 SMBus and I2C Compatibility

The major differences between SMBus and I2C devices are highlighted here. For more information, refer to the SMBus 2.0 specification.

1. CAP1298 supports I

2. Minimum frequency for SMBus communications is 10kHz.

C fast mode at 400kHz. This covers the SMBus max time of 100kHz.

3. The SMBus client protocol will reset if the clock is held low longer than 30ms (timeout condition). This can be enabled in the CAP1298 by setting the TIMEOUT bit in the Configuration register. I2C does not have a timeout.

4. The SMBus client protocol will reset if both the clock and the data line are high for longer than 200us (idle condition). This can be enabled in the CAP1298 by setting the TIMEOUT bit in the Configuration register. I

5. I

C devices do not support the Alert Response Address functionality (which is op tional for SMBus).

C devices support block read and write differently. I2C protocol allows for unlimited number of

6. I bytes to be sent in either direction. The SMBus protocol requires that an additional data byte indicating number of bytes to read / write is transmitted. The CAP1298 supports I

C does not have an idle condition.

3.3 SMBus Protocols

The CAP1298 is SMBus 2.0 compatible and supports Write Byte, Read Byte, Send Byte, and Receive Byte as valid protocols as shown below.

All of the below protocols use the convention in Table 3.1.

DATA SENT

TO DEVICE

Data sent Data sent

Table 3.1 Protocol Format

DATA SENT TO

THE HOST

C formatting only .

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Page 16

3.3.1 SMBus Write Byte

The Write Byte is used to write one byte of data to a specific register as shown in Table 3.2.

8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Table 3.2 Write Byte Protocol

START

SLAVE

ADDRESS WR

ACK

ADDRESS ACK

DATA ACK STOP

1 ->0 0101_000 0 0 XXh 0 XXh 0 0 -> 1

3.3.2 SMBus Read Byte

The Read Byte protocol is used to read one byte of data from the registers as show n in Table 3.3.

Table 3.3 Read Byte Protocol

START SLAVE

ADDRESS

WR ACK REGISTER

ADDRESS

ACK START CLIENT

ADDRESS

RD ACK REGISTER

DATA

NACK STOP

1->0 0101_000 0 0 XXh 0 1 ->0 0101_000 1 0 XXh 1 0 -> 1

3.3.3 SMBus Send Byte

The Send Byte protocol is used to set the internal address register pointer to the correct address location. No data is transferred during the Send Byte protocol as shown in Table 3.4.

APPLICATION NOTE: The Send Byte protocol is not functional in Deep Sleep (i.e., DSLEEP bit is set).

Table 3.4 Send Byte Protocol

START

SLAVE

ADDRESS WR ACK

ADDRESS ACK STOP

1 -> 0 0101_000 0 0 XXh 0 0 -> 1

3.3.4 SMBus Receive Byte

The Receive Byte protocol is used to read data from a register when the internal register address pointer is known to be at the right location (e.g. set via Send Byte). This is used for consecutive reads of the same register as shown in Table 3.5.

APPLICATION NOTE: The Receive Byte protocol is not functional in Deep Sleep (i.e., DSLEEP bit is set).

Table 3.5 Receive Byte Protocol

SLAVE

START

1 -> 0 0101_000 1 0 XXh 1 0 -> 1

DS01571A-page 16  2013 Microchip Technology Inc.

ADDRESS RD

ACK REGISTER DATA NACK STOP

Page 17

8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

3.4 I2C Protocols

The CAP1298 supports I2C Block Read and Block Write. The protocols listed below use the convention in Table 3.1.

3.4.1 Block Read

The Block Read is used to read multiple data bytes from a group of contiguous registers as sh own in

Table 3.6.

APPLICATION NOTE: When using the Block Read protocol, the internal address pointer will be automatically

incremented after every data byte is received. It will wrap from FFh to 00h.

Table 3.6 Block Read Protocol

START SLAVE

ADDRESS

WR ACK REGISTER

ADDRESS

ACK START SLAVE

ADDRESS

RD ACK REGISTER

DATA

1->0 0101_000 0 0 XXh 0 1 ->0 0101_000 1 0 XXh

ACK REGISTER

DATA

ACK REGISTER

DATA

ACK REGISTER

DATA

ACK . . . REGISTER

DATA

NACK STOP

0 XXh 0 XXh 0 XXh 0 . . . XXh 1 0 -> 1

3.4.2 Block Write

The Block Write is used to write multiple data bytes to a group of contiguous registers as shown in

Table 3.7.

APPLICATION NOTE: When using the Block Write protocol, the internal address pointer will be automatically

incremented after every data byte is received. It will wrap from FFh to 00h.

Table 3.7 Block Write Protocol

ADDRESS ACK

START

SLAVE

ADDRESS WR

ACK

1 ->0 0101_000 0 0 XXh 0 XXh 0

DATA

ACK

DATA ACK . . .

DATA ACK STOP

DATA ACK

XXh 0 XXh 0 . . . XXh 0 0 -> 1

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Chapter 4 General Description

The CAP1298 is a multiple channel capacitive touch sensor. It contains eight (8) individual capacitive touch sensor inputs with programmable sensitivity for use in touch sensor applications. Each sensor input is calibrated to compensate for system parasitic capacitance and automatically recalibrated to compensate for gradual environmental changes.

In addition, the CAP1298 can be configured to detect proximity on one or more channels with an optional signal guard to reduce noise sensitivity.

The CAP1298 has Active and Standby states, each with its own sensor input configuration controls. The Combo state allows a combination of sensor input controls to be used which enab les one or more sensor inputs to operate as buttons while another sensor input is operating as a proximity detector. Power consumption in the Standby and Combo states is dependent on the number of sensor inputs enabled as well as averaging, sampling time, and cycle time. Deep Sleep is the lowest power state available, drawing 5µA (typical) of current. In this state, no sensor inputs are active, and communications will wake the device.

The device communicates with a host controller using SMBus / I device for updated information at any time or it may configure the device to flag an in terrupt whenever a touch is detected on any sensor pad.

Datasheet

C. The host controller may poll the

A typical system diagram is shown in Figure 4.1.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

CAP1298

CS7

SMDATA

SMCLK

Embedded

Controller

ALERT#

CS8

CS3

CS2

CS1

CS4

CS6

Touch Button

SG*

Proximity

Sensor

VDDGND

3.0V to 5.5V

* CS5 / SG is a multi-function pin. If not using the signal guard show n here, CS5 can be another touch button.

10kOhm resistors

3.0V to 5.5V

1.0uF0.1uF

Datasheet

Figure 4.1 System Diagram for CAP1298

4.1 Power States

The CAP1298 has 4 power states depending on the status of the STBY, COMBO, and DSLEEP bits (see Section 5.1, "Main Control Register"). When the device transitions between power states, previously detected touches (for channels that are being de-activated) a re cleared a nd the sensor i nput status bits are reset.

1. Active - The normal mode of operation. The device is monitoring capacitive sensor inputs enabled in the Active state (see Section 5.7, "Sensor Input Enable Register").

2. Standby - When the STBY bit is set, the device is monitoring the capacitive sensor in puts enabled in the Standby state (see Section 5.22, "Standby Channel Register"). Interrupts can still be generated based on the enabled channels. The device will still respond to communications normally and can be returned to the Active state of operation by clearing the STBY bit. Power consumption in this state is dependent on the number of sensor inputs enabled as well as averaging, sampling time, and cycle time.

3. Combo - When the COMBO bit is set, the device is monitoring capacitive sensor inputs enabled in the Active state as well as inputs enabled in the Standby state (hence the name “Combo”). Interrupts can still be generated based on the enabled channels. The device wi ll still respond to

 2013 Microchip Technology Inc. DS01571A-page 19

communications normally and can be returned to the Active state of operation by clearing the

Page 20

COMBO bit. Power consumption in this state is dependent on the number of sensor inputs enabled

BOR

PWRT

GND

Undefined

SYSRST

POR

PORR

BORDCTPWRT

as well as averaging, sampling time, and cycle time.

4. Deep Sleep - When the DSLEEP bit is set, the device is in its lowest power state. It is not monitoring any capacitive sensor inputs. While in Deep Sleep, the CAP1298 can be awakened by SMBus communications targeting the device. This will not cause the DSLEEP to be cleared so the device will return to Deep Sleep once all communications have stopped. The device can be returned to the Active state of operation by clearing the DSLEEP bit.

4.2 Reset

The Power-On Reset (POR) circuit holds the device in reset until VDD has reached an acceptable level, Power-on Reset Release Voltage (V used to extend the start-up period until all device operation conditions have been met. Th e power-up timer starts after V

The Brown-Out Reset (BOR) circuit holds the device in reset when V for longer than the BOR reset delay (t up timer is started again and must finish before reset is released, as shown in Figure 4.2.

reaches V

8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

), for minimum operation. The power-up timer (PWRT) is

PORR

. POR and PORR with slow rising VDD is shown in Figure 4.2.

PORR

falls to a minimum level, V

). After a BOR, when VDD rises above V

BORDC

PORR

, the power-

BOR

Figure 4.2 POR and PORR With Slow Rising V

and BOR with Falling V

4.3 Capacitive Touch Sensing

The CAP1298 contains eight (8) independent capacitive touch sensor inputs. Each sensor input has dynamic range to detect a change of capacitance due to a touch. Additionally, each sensor input can be configured to be automatically and routinely recalibrated.

4.3.1 Capacitive Touch Sensing Settings

Controls for managing capacitive touch sensor inp uts are determined by the power state.

4.3.1.1 Active State Sensing Settings

The Active state is used for normal operation. Sensor inputs being monitored are determined by the Sensor Input Enable Register (see Section 5.7, "Sensor Input Enable Register"). Sensitivity is controlled by the Sensitivity Control Register (see Section 5.5, "Sensitivity Control Register"). Averaging, sample time, and cycle time are controlled by the Averaging and Sampling Configuration Register (see Section 5.10, "Averaging and Sampling Configuration Register"). Each channel can have a separate touch detection threshold, as defined in the Sensor Input Threshold registers (see Section

5.20, "Sensor Input Threshold Registers").

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

4.3.1.2 Standby State Sensing Settings

The Standby state is used for standby operation. In general, fewer sensor inputs are enabled, and they are programmed to have more sensitivity. Sensor inputs being monitored are determined by the Standby Channel Register (see Section 5.22, "Standby Channel Register"). Sensitivity is controlled by the Standby Sensitivity Register (see Section 5.24, "Standby Sensitivity Register"). Averaging, sample time, and cycle time are controlled by the Averaging and Sampling Configuration Register (see Section

5.23, "Standby Configuration Register"). There is one touch detection threshold, which applies to all

sensors enabled in Standby, as defined in the Standby Threshold Register (see Section 5.25, "Standby

Threshold Register").

4.3.1.3 Combo State Sensing Settings

The Combo state is used when a combination of proximity detection and norm al button operation is required. When the COMBO bit is set, the sensing cycle includes sensor inputs enabled in the Active state as well as sensor inputs enabled in the Standby state. Sensor inputs enabled in the Active state will use the Active settings described in Section 4.3.1.1, "Active State Sensing Settings". Sensor inputs enabled in the Standby state will use the Standby settings described in Section 4.3.1.2, "Standby State

Sensing Settings". If a sensor input is enabled in both th e Active state and in the Standby state, the

Active state settings will be used in Combo state. The programmed cycle time is determined by STBY_CY_TIME[1:0].

The Combo state also has two gain settings. When the COMBO bit is set, the GAIN[1:0] control only applies to the sensors enabled in the Active state, and the C_GAIN[1:0] control applies to the sensors enabled in the Standby state.

4.3.2 Sensing Cycle

Except when in Deep Sleep, the device automatically initiates a sensing cycle and repeats the cycle every time it finishes. The cycle polls through each enabled sensor input starting with CS1 and extending through CS8. As each capacitive touch sensor i nput is polled, its measurement is compared against a baseline “not touched” measurement. If the delta measurement is large enou gh to exceed the applicable threshold, a touch is detected and an interrupt can be generated (see Section 4.9.2,

"Capacitive Sensor Input Interrupt Behavior").

The sensing cycle time is programmable (see Section 5.10, "Averaging and Sampling Configuration

less than the cycle time, the device is placed into a lower power state for the remainder of the sensi ng cycle. If the number of active sensor inputs cannot be sampled within the specified cycle time, the cycle time is extended and the device is not placed in a lower power state.

4.4 Sensor Input Calibration

Calibration sets the Base Count Registers (Section 5.26, "Sensor Input Base Count Registers") which contain the “not touched” values used for touch detection comparisons. Calibration automatically occurs after a power-on reset (POR), when sample time is changed, when the gain is changed, when the calibration sensitivity is changed, and whenever a sensor input is newly enabled (for example, when transitioning from a power state in which it was disabled to a power state in which it is enab led). During calibration, the analog sensing circuits are tuned to the capacitance of the untouched pad. Then, samples are taken from each sensor input so that a base count can be established. After calibration, the untouched delta counts are zero.

APPLICATION NOTE: During the calibration routine, the sensor inputs will not detect a press for up to 200ms and

the Sensor Base Count Register values will be invalid. In addition, any press on the corresponding sensor pads will invalidate the calibration.

The host controller can force a calibration for selected sensor inputs at any time using the Calibrati on Activate and Status Register (Section 5.11, "Calibration Activate and Status Register"). When a bit is

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

set, the corresponding capacitive touch sensor input will be calibrated (both analog and digital). The bit is automatically cleared once the calibration routine has successfully finished.

If analog calibration fails for a sensor input, the corresponding bit is not cleared in the Calibration Activate and Status Register, and the ACAL_FAIL bit is set in the General Status Register (Section 5.2,

"Status Registers"). An interrupt can be generated. Analog calibration will fail if a noise bit is set or if

the calibration value is at the maximum or minimum value. If digital calibrati on fails to generate base counts for a sensor input in the operating range, which is +

Table 4.1), indicating the base capacitance is out of range, the corresponding BC_OUTx bit is set in

the Base Count Out of Limit Register (Section 5.18, "Base Count Out of Limit Register"), and the BC_OUT bit is set in the General Status Register (Section 5.2, "Status Registers"). An interrupt can be generated. By default, when a base count is out of limit, analog calibration is repeated for the sensor input; alternatively, the sensor input can be sampled using the out of limit base count (Section

5.6, "Configuration Registers"). Calibration sensitivity can be ad justed for each sensor input based on

capacitive touch pad capacitance.

Table 4.1 Ideal Base Counts

IDEAL BASE COUNT SAMPLE TIME

3,200 320us

12.5% from the ideal base count (see

6,400 640us 12,800 1.28ms 25,600 2.56ms

During normal operation there are various options for reca librating the capacitive touch sensor inputs. Recalibration is a digital adjustment of the base counts so that the untouched delta count is zero. After a recalibration, if a sensor input’s base count has shifted + calibration will be performed on the sensor input.

12.5% from the ideal base count, a full

4.4.1 Automatic Recalibration

Each sensor input is regularly recalibrated at a programmable rate (see CAL_CFG[2:0] in Section 5.19,

"Recalibration Configuration Register"). By default, the recalibration routine stores the average 64

previous measurements and periodically updates the base “not touched” setting for the capacitive touch sensor input.

APPLICATION NOTE: Automatic recalibration only works when the delta count is below the active sensor input

threshold. It is disabled when a touch is detected.

4.4.2 Negative Delta Count Recalibration

It is possible that the device loses sensitivity to a touch. This may happen as a result of a noisy environment, recalibration when the pad is touched but delta counts do not exceed the threshold, or other environmental changes. When this occurs, the base untouched sensor input may generate negative delta count values. The NEG_DELTA_CNT[1:0] bits (see Section 5.19, "Recalibration

Configuration Register") can be set to force a recalibration after a specified number of consecutive

negative delta readings. After a delayed recalibration (see Section 4.4.3, "Delayed Recalibration") the negative delta count recalibration can correct after the touch is released.

APPLICATION NOTE: During this recalibration, the device will not respond to touches.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

CAP129X Device

CS pin

SIGNAL_GUARD

CS pin

Touch Pad

Datasheet

4.4.3 Delayed Recalibration

It is possible that a “stuck button” occurs when some thing is placed on a butto n which causes a touch to be detected for a long period. By setting the MAX_DUR_EN bit (see Section 5.6, "Configuration

Registers"), a recalibration can be forced when a touch is held on a button for longer than the duration

specified in the MAX_DUR[3:0] bits (see Section 5.8, "Sensor Input Configuration Register"). Note 4.1 Delayed recalibration only works when the delta count is above the active sensor input

threshold. If enabled, it is invoked when a sensor pad touch is held longer than the MAX_DUR bit settings.

Note 4.2 For the power button, which requires that the button be held longer than a reg ular button,

the time specified by the MAX_DUR[3:0] bits is added to the time required to trigger the qualifying event. This will prevent the power butto n from being recalibrated during the time it is supposed to be held.

4.5 Proximity Detection

Each sensor input can be configured to detect changes in capacitance due to proximity of a touch. This circuitry detects the change of capacitance that is generated as an object approaches, but does not physically touch, the enabled sensor pad(s). Generally, sensor inputs used to detect proximity have physically larger pads than standard buttons. In addition, gain should be increased to increase sensitivity. To improve the signal, the signal guard feature ma y be used.

4.5.1 Signal Guard

The signal guard isolates the signal from virtual grounds, as shown in Figure 4.3. It can be used to isolate the proximity antenna from nearby conductive surfaces tha t would otherwise attenuate the efield.

4.6 Power Button

Figure 4.3 Signal Guard

The CAP1298 has a “power button” feature. In general, buttons are set for quick response to a touch, especially when buttons are used for number keypads. However, there are cases where a quick response is not desired, such as when accidentally brushing the power button causes a device to turn off or on unexpectedly.

The power button feature allows a sensor input to be designated as the “po wer button” (see Section

5.27, "Power Button Register"). The power button is configured so that a touch must be held on the

button for a designated period of time before an interrupt is generated; different times can be sel ected

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

for the Standby and the Active states (see Section 5.28, "Power Button Configuration Register"). The feature can also be enabled / disabled for both states separately.

APPLICATION NOTE: For the power button feature to work in the Standby and/or Active states, the sensor input

must be enabled in the applicable state. If the power button feature is enabled for both Standby and Active and the COMBO bit is set, the Standby power button settings will be used.

After the designated power button has been held for the designated time, an interrupt is generated and the PWR bit is set in the General Status Register (see Section 5.2, "Status Registers").

4.7 Multiple Touch Pattern Detection

The multiple touch pattern (MTP) detection circuitry can be used to detect lid closure or oth er similar events. An event can be flagged based on either a minimum number of sensor i nputs or on specific sensor inputs simultaneously exceeding an MTP threshold or having their Noise Fla g Status Register bits set. An interrupt can also be generated. During an MTP event, all touches are blocked (see

Section 5.16, "Multiple Touch Pattern Configuration Register").

4.8 Noise Controls

4.8.1 Low Frequency Noise Detection

Each sensor input has a low frequency noise detector that will sense if low freque ncy noise is injected onto the input with sufficient power to corrupt the readings. By default, if this occurs, the device will reject the corrupted sample (see DIS_ANA_NOISE bit in Section 5.6.1, "Configuration - 20h") and the corresponding bit is set to a logic ‘1’ in the Noise Flag Status register (see SHOW_RF_NOISE bit in

Section 5.6.2, "Configuration 2 - 44h").

4.8.2 RF Noise Detection

Each sensor input contains an integrated RF noise detector. This block will detect injected RF noise on the CS pin. The detector threshold is dependent upon the noise frequency. By default, if RF noise is detected on a CS line, that sample is removed and not compared against the threshold (see DIS_RF_NOISE bit in Section 5.6.2, "Configuration 2 - 44h").

4.8.3 Noise Status and Configuration

The Noise Flag Status (see Section 5.3, "Noise Flag Status Registers") bits can be used to indicate RF and/or other noise. If the SHOW_RF_NOISE bit in the Configuration Register (see Section 5.6,

"Configuration Registers") is set to 0, the Noise Flag Status bit for the capacitive sensor input is set if

any analog noise is detected. If the SHOW_RF_NOISE bit is set to 1, the Noise Flag Status bits will only be set if RF noise is detected.

The CAP1298 offers optional noise filtering controls for both analog an d digital noise. For analog noise, there are options for whether the data should be considered invalid. By default, the

DIS_ANA_NOISE bit (see Section 5.6.1, "Configuration - 20h") will block a touch on a sensor input if low frequency analog noise is detected; the sample is discarded. By default, the DIS_RF_NOISE bit (see Section 5.6.2, "Configuration 2 - 44h") will block a touch o n a sensor input if RF noise is detected; the sample is discarded.

For digital noise, sensor input noise thresholds can be set (see Section 5.21, "Sensor Input Noise

Threshold Register"). If a capacitive touch sensor input exceeds the Sensor Noise Threshold but does

not exceed the touch threshold (Sensor Threshold (see Section 5.20, "Sensor Input Threshold

Registers") in the Active state or Sensor Standby Threshold in the Standby state (Section 5.25, "Standby Threshold Register")), it is determined to be caused by a noise spike. The DIS_DIG_NOISE

bit (see Section 5.6.1, "Configuration - 20h") can be set to discard samples that indicate a noise spike

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

so they are not used in the automatic recalibration routine (see Section 4.4.1, "Automatic

Recalibration").

4.9 Interrupts

Interrupts are indicated by the setting of the INT bit in the Main Control Register (see Section 5.1,

"Main Control Register") and by assertion of the ALERT# pin. The ALERT# pin is cleared when the

INT bit is cleared by the user. When the INT bit is cleared by the user, status bits may be cleared (see

Section 5.2, "Status Registers").

4.9.1 ALERT# Pin

The ALERT# pin is an active low output that is driven when an interrupt event is de tected.

4.9.2 Capacitive Sensor Input Interrupt Behavior

Each sensor input can be programmed to enable / disable interrupts (see Section 5.12, "Interrupt

Enable Register").

When enabled for a sensor input and the sensor input is not the designated power button, interrupts are generated in one of two ways:

1. An interrupt is generated when a touch is detected and, as a user selectable option, when a release is detected (by default - see INT_REL_n in Section 5.6.2, "Configuratio n 2 - 44h"). See Figure 4.5.

2. If the repeat rate is enabled then, so long as the touch is held, another interrupt will be generated based on the programmed repeat rate (see Figure 4.4).

When the repeat rate is enabled for a sensor inpu t (see Section 5.13, "Repeat Rate Enable Register"), the device uses an additional control called MPRESS that determines whether a touch is flagged as a simple “touch” or a “press and hold” (see Section 5.9, "Sensor Input Configuration 2 Register"). The MPRESS[3:0] bits set a minimum press timer. When the button is touched, the timer begins. If the sensor pad is released before the minimum press timer expires, it is flagged as a touch and an interrupt (if enabled) is generated upon release. If the sensor input detects a touch for longer than this timer value, it is flagged as a “press and hold” event. So long as the touch is held, interrupts will be generated at the programmed repeat rate (see Section 5.8, "Sensor Input Configuration Register") and upon release (if enabled).

If a sensor input is the designated power button, an interrupt is not generated as soon as a touch is detected and repeat rate is not applicable. See Section 4.9.3, "Inte rrupts for the Power Button".

APPLICATION NOTE: Figure 4.4 and Figure 4.5 show default operation which is to generate an interrupt upon

sensor pad release.

APPLICATION NOTE: The host may need to poll the device twice to dete rmine that a release has been detected.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Touch Detected

INT bit

Button Status

Write to INT bit

Sensing Cycle

(35ms)

Min Press Setting

(280ms)

Interrupt on

Touch

Button Repeat Rate

(175ms)

Button Repeat Rate

(175ms)

Interrupt on

Release

(optional)

ALERT# pin

Touch Detected

INT bit

Button Status

Write to INT bit

Sensing Cycle

(35ms)

Interrupt on

Touch

Interrupt on

Release

(optional)

ALERT# pin

Datasheet

Figure 4.4 Sensor Interrupt Behavior - Repeat Rate Enabled

Figure 4.5 Sensor Interrupt Behavior - No Repeat Rate Enabled

4.9.3 Interrupts for the Power Button

4.9.4 Interrupts for Multiple Touch Pattern Detection

DS01571A-page 26  2013 Microchip Technology Inc.

Interrupts are automatically enabled for the power button when the featu re is enabled (see Se ction 4 .6,

"Power Button"). A touch must be held on the power button for the designated period of time before

an interrupt is generated.

An interrupt can be generated when the MTP pattern is matched (see Section 5.16, "Mul tiple Touch

Pattern Configuration Register").

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

4.9.5 Interrupts for Sensor Input Calibration Failures

An interrupt can be generated when the ACAL_FAIL bit is set, indicating the failure to complete analog calibration of one or more sensor inputs (see Section 5.2, "Status Registers"). This interrupt can be enabled by setting the ACAL_FAIL_INT bit (see Section 5.6, "Configuration Registers").

An interrupt can be generated when the BC_OUT bit is set, indicating the base count is o ut of limit for one or more sensor inputs (see Section 5.2, "Status Registers"). This interrupt can be enabled by setting the BC_OUT_INT bit (see Section 5.6, "Configuration Registers").

4.9.6 Interrupts for Reset

When the CAP1298 comes out of reset, an interru pt is generated, and the RESET bit is set.

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Chapter 5 Register Description

The registers shown in Table 5.1 are accessible through the communications protocol. An entry of ‘-’ indicates that the bit is not used and will always read ‘0’.

Table 5.1 Register Set in Hexadecimal Order

Datasheet

ADDRESS R/W REGISTER NAME FUNCTION

00h R/W Main Con trol

02h R/W General Status Stores general status bits 00h Page 33

03h R Sensor Input Status

0Ah R Noise Flag Status

10h R

11h R

12h R

13h R

14h R

15h R

Sensor Input 1 Delta

Count

Sensor Input 2 Delta

Count

Sensor Input 3 Delta

Count

Sensor Input 4 Delta

Count

Sensor Input 5 Delta

Count

Sensor Input 6 Delta

Count

Controls power states and indicates

an interrupt

Returns the state of the sampled

capacitive touch sensor inputs

Stores the noise flags for sensor

inputs

Stores the delta count for CS1 00h Page 35

Stores the delta count for CS2 00h Page 35

Stores the delta count for CS3 00h Page 35

Stores the delta count for CS4 00h Page 35

Stores the delta count for CS5 00h Page 35

Stores the delta count for CS6 00h Page 35

DEFAULT

VALUE PAGE

00h Page 31

00h Page 33

00h Page 34

16h R

17h R

1Fh R/W Sensitivity Control

20h R/W Configuration Controls genera l functionality 20h Page 37

21h R/W Sensor Input Enable

22h R/W

23h R/W

24h R/W

DS01571A-page 28  2013 Microchip Technology Inc.

Sensor Input 7 Delta

Count

Sensor Input 8 Delta

Count

Sensor Input Configuration

Sensor Input

Configuration 2

Averaging and

Sampling Config

Stores the delta count for CS7 00h Page 35

Stores the delta count for CS8 00h Page 35

Controls the sensitivity of the

threshold and delta counts and data

scaling of the base counts

Controls which sensor inputs are

monitored in Active

Controls max duration and auto-

repeat delay

Controls the MPRESS (“press and

hold”) setting

Controls averaging and sampling

window for Active

2Fh Page 36

FFh Page 39

A4h Page 39

07h Page 41

39h Page 42

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Table 5.1 Register Set in Hexa decimal Order (continued)

ADDRESS R/W REGISTER NAME FUNCTION

26h R/W

Calibration Activate

and Status

27h R/W Interrupt Enable

28h R/W Repeat Rate Enable

29h R/W Sig nal Guard Enable

2Ah R/W

2Bh R/W

Multiple Touch

Configuration

Multiple T ouch Pattern

Configuration

Forces calibration for capacitive

touch sensor inputs and indicates

calibration failure

Determines which capacitive sensor

inputs can generate interrupts

Enables repeat rate for specific

sensor inputs

Enables the signal guard for specific

sensor inputs

Determines the number of

simultaneous touches to flag a

multiple touch condition

Determines the multiple touch

pattern (MTP) configuration

Determines the pattern or number of

2Dh R/W Multiple Touch Pattern

sensor inputs used by the MTP

circuitry

2Eh R

Base Count Out of

Limit

Indicates whether sensor inputs

have a base count out of limit

DEFAULT

VALUE PAGE

00h Page 44

FFh Page 45

00h Page 46

80h Page 47

00h Page 47

FFh Page 49

00h Page 50

2Fh R/W

30h R/W

31h R/W

32h R/W

33h R/W

34h R/W

35h R/W

36h R/W

37h R/W

38h R/W

Recalibration Configuration

Sensor Input 1

Threshold

Sensor Input 2

Threshold

Sensor Input 3

Threshold

Sensor Input 4

Threshold

Sensor Input 5

Threshold

Sensor Input 6

Threshold

Sensor Input 7

Threshold

Sensor Input 8

Threshold

Sensor Input Noise

Threshold

Standby Configuration Registers

Determines recalibration timing and

sampling window

Stores the touch detection threshold

for Active for CS1

Stores the touch detection threshold

for Active for CS2

Stores the touch detection threshold

for Active for CS3

Stores the touch detection threshold

for Active for CS4

Stores the touch detection threshold

for Active for CS5

Stores the touch detection threshold

for Active for CS6

Stores the touch detection threshold

for Active for CS7

Stores the touch detection threshold

for Active for CS8

Stores controls for selecting the

noise threshold for all sensor inputs

8Ah Page 50

40h Page 52

40h

01h Page 52

40h R/W Standby Channel

 2013 Microchip Technology Inc. DS01571A-page 29

Controls which sensor inputs are

enabled for Standby

00h Page 53

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Table 5.1 Register Set in Hexa decimal Order (continued)

Datasheet

ADDRESS R/W REGISTER NAME FUNCTION

41h R/W Standby Configuration

42h R/W Standby Sensitivity

43h R/W Standby Threshold

44h R/W Configuration 2

Controls averaging and sensing

cycle time for Standby

Controls sensitivity settings used for

Standby

Stores the touch detection threshold

for Standby

Stores additional configuration

controls for the device

Base Count Registers

50h R

51h R

52h R

53h R

54h R

Sensor Input 1 Base

Count

Sensor Input 2 Base

Count

Sensor Input 3 Base

Count

Sensor Input 4 Base

Count

Sensor Input 5 Base

Count

Stores the reference count value for

sensor input 1

Stores the reference count value for

sensor input 2

Stores the reference count value for

sensor input 3

Stores the reference count value for

sensor input 4

Stores the reference count value for

sensor input 5

DEFAULT

VALUE PAGE

39h Page 54

02h Page 55

40h Page 56

40h Page 37

C8h Page 56

55h R

56h R

57h R

Sensor Input 6 Base

Count

Sensor Input 7 Base

Count

Sensor Input 8 Base

Count

Stores the reference count value for

sensor input 6

Stores the reference count value for

sensor input 7

Stores the reference count value for

sensor input 8

C8h Page 56

Power Button Registers

60h R/W Powe r Button Specifies the power button 00h Page 57

61h R/W

Power Button Configuration

Configures the power button feature 22h Page 58

Calibration Sensitivity Configuration Registers

80h R/W

81h R/W

Calibration Sensitivity

Configuration 1

Calibration Sensitivity

Configuration 2

Stores calibration sensitivity settings

for proximity

Stores calibration sensitivity settings

for proximity

00h Page 60

00h

Page 60

Calibration Registers

B1h

B2h

R Sensor Input 1

Calibration

R Sensor Input 2

Calibration

Stores the upper 8-bit calibration

value for CS1

Stores the upper 8-bit calibration

value for CS2

00h Page 59

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Table 5.1 Register Set in Hexa decimal Order (continued)

ADDRESS R/W REGISTER NAME FUNCTION

B3h

B4h

B5h

B6h

B7h

B8h

B9h

BAh

FDh R Product ID

R Sensor Input 3

Calibration

R Sensor Input 4

Calibration

R Sensor Input 5

Calibration

R Sensor Input 6

Calibration

R Sensor Input 7

Calibration

R Sensor Input 8

Calibration

R Sensor Input

Calibration LSB 1

R Sensor Input

Calibration LSB 2

Stores the upper 8-bit calibration

value for CS3

Stores the upper 8-bit calibration

value for CS4

Stores the upper 8-bit calibration

value for CS5

Stores the upper 8-bit calibration

value for CS6

Stores the upper 8-bit calibration

value for CS7

Stores the upper 8-bit calibration

value for CS8

Stores the 2 LSBs of the calibration

value for CS1 - CS4

Stores the 2 LSBs of the calibration

value for CS5 - CS8

ID Registers

Stores a fixed value that identifies

the CAP1298-1

DEFAULT

VALUE PAGE

00h Page 59

71h Page 60

FEh R Manufacturer ID

FFh R Revision

During power-on reset (POR), the default values are stored in the registers. A POR is i nitiated when power is first applied to the part and the voltage on the VDD supply surpasses the POR level as specified in the electrical characteristics.

When a bit is “set”, this means it’s at a logic ‘1’. When a bit is “cleared”, this means it’s at a logic ‘0’.

Stores a fixed value that identifies

MCHP

Stores a fixed value that represents

the revision number

5Dh Page 61

00h Page 61

5.1 Main Control Register

Ta b le 5.2 Main Control Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

00h R/W Main Control GAIN[1:0] STBY DSLEEP C_GAIN[1:0] COMBO INT 00h

The Main Control register controls the primary power state of the device (see Section 4.1, "Power

States").

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If more than one power state bit is set, the actual power state will be as shown in Table 5.3, "Power

State Bit Overrides".

T able 5.3 Power State Bit Overrides

DSLEEP COMBO STBY POWER STATE

000Active 0 0 1 Standby 0 1 X Combo 1 X X DSleep

Bits 7 - 6 - GAIN[1:0] - Controls the analog gain used by the capacitive touch sensing circuitry. As the gain is increased, the effective sensitivity is likewise increased as a smaller delta capacitance is required to generate the same delta count values. The sensitiv ity settings may need to be adjusted along with the gain settings such that data overflow does not occur.

APPLICATION NOTE: The GAIN[1:0] settings apply to both Standby and Active states, unless the COMBO bit is

set. When the COMBO bit is set, this control only applies to the sensors enabled in the Active state, and the C_GAIN[1:0] control applies to the sensors enabled in the Standby state.

APPLICATION NOTE: Whenever the gain settings change, the device will recalibrate all sensor inputs as if they

had no base count.

Table 5.4 GAIN and C_GAIN Bit Decode

GAIN[1:0] OR C_GAIN[1:0]

CAPACITIVE TOUCH SENSOR INPUT GAIN10

00 1 01 2 10 4 11 8

Bit 5 - STBY - Enables Standby.

 ‘0’ (default) - The device is not in the Standby state.  ‘1’ - The device is in the Standby state. Capacitive touch sensor input scanning is limited to the

sensor inputs set in the Standby Channel register (see Section 5.22, "Standby Channel Register"). The status registers will not be cleared until read. Sensor inputs that are no longer sampled will flag a release and then remain in a non-touched state.

Bit 4 - DSLEEP - Enables Deep Sleep.

 ‘0’ (default) - The device is not in the Deep Sleep state.  ‘1’ - The device is in the Deep Sleep state. All sensor input scanning is disabled. Th e status

registers are automatically cleared and the INT bit is cleared..

Bits 3 - 2 - C_GAIN[1:0] - When the COMBO bit is set, this bit controls the analog gain used for capacitive touch sensor inputs enabled in the Standby state. As the gain is increased, the effective sensitivity is likewise increased as a smaller delta capacitance is required to generate the same delta

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count values. The Standby sensitivity settings may need to be adjusted along with the gain settings such that data overflow does not occur.

APPLICATION NOTE: The C_GAIN[1:0] setting is only used if the COMBO bit is set. When the COMBO bit is set,

this control only applies to the sensors enabled in the Standby state, and the GAIN[1:0] control applies to the sensors enabled in the Active state.

Bit 1 - COMBO - Enables Combo state (see Section 4.3.1.3, "Combo State Sensing Settings").

 ‘0’ (default) - The device is not in the Combo state.  ‘1’ - The device is in the Combo state. The device is monitoring sensor inputs enabled in th e Active

state (see Section 5.7, "Sensor Input Enable Register") as well as those enabl ed in the Standby state (see Section 5.22, "Standby Channel Register"). The status registers will not be cleared until read. Sensor inputs that are no longer sampled will flag a release and then remain in a non-touched state.

Bit 0 - INT - Indicates that there is an interrupt (see Section 4.9, "Interrupts"). When this bit is set, it asserts the ALERT# pin. If a channel detects a touch but interrupts are not enabled for that channel (see Section 5.12, "Interrupt Enable Register"), no a ction is taken. This bit is cleared by writing a logic ‘0’ to it. When this bit is cleared, the ALERT# pin will be deasserted, and all status registers will be cleared if the condition has been removed.

 ‘0’ - No interrupt pending.  ‘1’ - An interrupt condition occurred, and the ALERT# pin has be en asserted.

5.2 Status Registers

Table 5.5 Status Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0

02h R General Status -

03h R

Sensor Input

Status

CS8 CS7 CS6 CS5 CS4 CS3 CS2 CS1 00h

All status bits are cleared when the device enters Deep Sleep (DSLEEP = ‘1’ - see Section 5.1, "Main

Control Register").

5.2.1 General Status - 02h

Bit 6 - BC_OUT - Indicates that the base count is out of limit for one or more enabled sensor inputs (see Section 4.4, "Sensor Input Calibration"). Thi s bit will not be cleared until all enabled sensor inpu ts have base counts within the limit.

 ‘0’ - All enabled sensor inputs have base counts in the operating range.  ‘1’ - One or more enabled sensor inputs has the base count out of limit. A status bit is set in the

Base Count Out of Limit Register (see Section 5.18, "Base Count Out of Limit Register").

Bit 5 - ACAL_FAIL - Indicates analog calibration failure for one or more enabled sensor inputs (see

Section 4.4, "Sensor Input Calibration"). This bit will not be cleared unti l all enabled sensor inputs have

successfully completed analog calibration.

 ‘0’ - All enabled sensor inputs were successfully calibrated.  ‘1’ - One or more enabled sensor inputs failed analog calibration. A status bit is set in the

Calibration Active Register (see Section 5.11, "Calibration Activate and Status Register").

BC_

OUT

ACAL _FAIL

PWR RESET MULT MTP TOUCH 00h

DEFAULT

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Bit 4 - PWR - Indicates that the designated power button has been held for the de signated time (see

Section 4.6, "Power Button"). This bit will cause the INT bit to be set. This bit is cleare d when the INT

bit is cleared if there is no longer a touch on the power button.

 ‘0’ - The power button has not been held for the required time or is not enabled.  ‘1’ - The power button has been held for the required time.

Bit 3 - RESET - Indicates that the device has come out of reset. This bit is set when the device exits a POR state. This bit will cause the INT bit to be set and is cleared when the INT bit is cleared.

Bit 2 - MULT - Indicates that the device is blocking detected touches due to the Multiple Touch detection circuitry (see Section 5.15, "Multiple Touch Configuration Register"). This bit will not cause the INT bit to be set and hence will not cause an interrupt.

Bit 1 - MTP - Indicates that the device has detected a number of sensor inputs that exceed the MTP threshold either via the pattern recognition or via the number of sensor inputs (see Section 5.16,

"Multiple Touch Pattern Configuration Register"). This bit will cause the INT bit to be set if the

MTP_ALERT bit is also set. This bit is cleared when the INT bit is cleared if the condition that caused it to be set has been removed.

Bit 0 - TOUCH - Indicates that a touch was detected. This bit is set if any bit in the Sensor Input Status register is set.

5.2.2 Sensor Input Status - 03h

Datasheet

The Sensor Input Status Register stores status bits that indicate a touch has been detected. A value of ‘0’ in any bit indicates that no touch has been detecte d. A value of ‘1’ in any bit indicates that a touch has been detected.

All bits are cleared when the INT bit is cleared and if a touch on the respe ctive capaciti ve touch sensor input is no longer present. If a touch is still detected, the bits will not be cleared (but this will not cause the interrupt to be asserted).

Bit 7 - CS8 - Indicates that a touch was detected on Sensor Input 8. Bit 6 - CS7 - Indicates that a touch was detected on Sensor Input 7. Bit 5 - CS6 - Indicates that a touch was detected on Sensor Input 6. Bit 4 - CS5 - Indicates that a touch was detected on Sensor Input 5. Bit 3 - CS4 - Indicates that a touch was detected on Sensor Input 4. Bit 2 - CS3 - Indicates that a touch was detected on Sensor Input 3. Bit 1 - CS2 - Indicates that a touch was detected on Sensor Input 2. Bit 0 - CS1 - Indicates that a touch was detected on Sensor Input 1.

5.3 Noise Flag Status Registers

Table 5.6 Noise Flag Status Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

0Ah R

Noise Flag

Status

CS8_

NOISE

CS7_

NOISE

CS6_

NOISE

CS5_

NOISE

CS4_

NOISE

CS3_

NOISE

CS2_

NOISE

CS1_

NOISE

00h

The Noise Flag Status registers store status bits that can be used to indicate that the analog block detected noise above the operating region of the analog d etector or th e R F noise de tector (see Section

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4.8.3, "Noise Status and Configuration"). These bits indicate that the most recently received data from

the sensor input is invalid and should not be used for touch detection. So long as the bit is set for a particular channel, the delta count value is reset to 00h and thus no touch is detected.

These bits are not sticky and will be cleared automatically if the analog block does not report a noise error.

APPLICATION NOTE: If the MTP detection circuitry is enabled, these bits count as sensor inputs above the MTP

threshold (see Section 4.7, "Multiple Touch Pattern Detection") even if the corresponding delta count is not. If the corresponding delta count also exceeds the MTP threshold, it is not counted twice.

APPLICATION NOTE: Regardless of the state of the Noise Status bits, if low frequency noise is detected on a

sensor input, that sample will be discarded unless the DIS_ANA_NOISE bit is set. As well, if RF noise is detected on a sensor input, that sample will be discarded unless the DIS_RF_NOISE bit is set.

5.4 Sensor Input Delta Count Registers

Table 5.7 Sensor Input Delta Count Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

10h R

11h R

12h R

13h R

14h R

15h R

16h R

17h R

Sensor Input 1

Delta Count

Sensor Input 2

Delta Count

Sensor Input 3

Delta Count

Sensor Input 4

Delta Count

Sensor Input 5

Delta Count

Sensor Input 6

Delta Count

Sensor Input 7

Delta Count

Sensor Input 8

Delta Count

The Sensor Input Delta Count registers store the delta count that is compared against the threshold used to determine if a touch has been detected. The count value represents a change in input due to the capacitance associated with a touch on one of the sensor inputs and is referenced to a calibrated base “not touched” count value. The delta is an instantaneous change and is updated once per sensor input per sensing cycle (see Section 4.3.2, "Sensing Cycle").

Sign 64 32 16 8 4 2 1 00h

The value presented is a standard 2’s complement number. In addition, the value is capped at a value of 7Fh. A reading of 7Fh indicates that the sensitivity settings are too high and should be adjusted accordingly (see Section 5.5).

The value is also capped at a negative value of 80h for negative d elta counts which may result upon a release.

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5.5 Sensitivity Control Register

Ta b le 5.8 Sensitivity Control Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

1Fh R/W Sensitivity Control - DELTA_SENSE[2:0] BASE_SHIFT[3:0] 2Fh

The Sensitivity Control register controls the sensitivity of a touch detecti on. Bits 6-4 DELTA_SENSE[2:0] - Controls the sensitivity of a touch detection for sensor inputs enabled

in the Active state. The sensitivity settings act to scale the relative delta count value higher or lower based on the system parameters. A setting of 000b is the most sensitive while a setting of 111b is the least sensitive. At the more sensitive settings, touches are detected for a smaller delta capacitance corresponding to a “lighter” touch. These settings are more sensitive to noise, h owever, and a noisy environment may flag more false touches with higher sensitivity levels.

APPLICATION NOTE: A value of 128x is the most sensitive setting available. At the most sensitive setti ngs, the

MSB of the Delta Count register represents 64 out of ~25,000 which co rresponds to a touch of approximately 0.25% of the base capacitance (or a capacitance). Conversely, a value of 1x is the least sensitive setting available. At these settings, the MSB of the Delta Count register corresponds to a delta count of 8192 counts out of ~25,000 which corresponds to a touch of approximately 33% of the base capacitance

ΔC of 3.33pF from a 10pF base capacitance).

(or a

ΔC of 25fF from a 10pF base

Table 5.9 DELTA_SENSE Bit Decode

DELTA_SENSE[2:0]

SENSITIVITY MULTIPLIER210

0 0 0 128x (most sensitive) 001 64x 0 1 0 32x (default) 011 16x 100 8x 101 4x 110 2x 1 1 1 1x - (least sensitive)

Bits 3 - 0 - BASE_SHIFT[3:0] - Controls the scaling and data presentation of the Base Count registers. The higher the value of these bits, the larger the range and the lower the resolution of the data presented. The scale factor represents the multiplier to the bit-weighting presented in these register descriptions.

APPLICATION NOTE: The BASE_SHIFT[3:0] bits normally do not need to be updated. These settings will not affect

touch detection or sensitivity. These bits are sometimes helpful in analyzing the Cap Sensing board performance and stability.

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Table 5.10 BASE_SHIFT Bit Decode

BASE_SHIFT[3:0]

00 0 0 1x 00 0 1 2x 00 1 0 4x 00 1 1 8x 01 0 0 16x 01 0 1 32x 01 1 0 64x 0 1 1 1 128x 1 0 0 0 256x

DATA SCALING

FACTOR32 1 0

All others

256x

(default = 1111b)

5.6 Configuration Registers

Table 5.11 Configuration Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0

20h R/W Configuration

44h R/W

Configuration

TIME

OUT

The Configuration registers control general glo bal functionality that affects the entire device.

5.6.1 Configuration - 20h

Bit 7 - TIMEOUT - Enables the timeout and idle functionality of the SMBus protocol.

 ‘0’ (default) - The SMBus timeout and idle functionality are disable d. The SMBus interface will not

time out if the clock line is held low. Likewise, it will not reset if both the data and clock lines are held high for longer than 200us.

 ‘1’ - The SMBus timeout and idle functionality are enabled. The SMBus interface will reset if the

clock line is held low for longer than 30ms. Likewise, it will reset if both the data and clock lines are held high for longer than 200us.

BC_

OUT_

RECAL

DIS_ DIG_

NOISE

BLK_

PWR_

CTRL

DIS_

ANA_

NOISE

BC_

OUT_

INT

MAX_

DUR_EN

SHOW_

RF_

NOISE

- - - 20h

DIS_

RF_

NOISE

ACAL _FAIL

_INT

INT_

REL_

DEFAULT

40h

Bit 5 - DIS_DIG_NOISE - Determines whether the digital noise threshold (see Section 5.21 , "Sensor

Input Noise Threshold Register") is used by the device. Setting this b it disables the feature.

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 ‘0’ - The digital noise threshold is used. If a delta count value exceeds the noise threshold but do es

not exceed the touch threshold, the sample is discarded and not used for the automatic recalibration routine.

 ‘1’ (default) - The noise threshold is disabled. Any delta count that is less than the touch threshold

is used for the automatic recalibrati on routine.

Bit 4 - DIS_ANA_NOISE - Determines whether the analog noise filter is enabled. Setting this bit disables the feature.

 ‘0’ (default) - If low frequency noise is detected by the analog block, the delta count on the

corresponding channel is set to 0. Note that this does not require that Noise Status bits be set.

 ‘1’ - A touch is not blocked even if low frequency noise is detected.

Bit 3 - MAX_DUR_EN - Determines whether the maximum duration recalibration is enabled.

 ‘0’ (default) - The maximum duration recalibration functionality is d isabled. A touch may be held

indefinitely and no recalibration will be performed on any sensor input.

 ‘1’ - The maximum duration recalibration functionality is enabled. If a touch is held for longer than

the MAX_DUR bit settings (see Section 5.8), the recalibration ro utine will be restarted (see Section

4.4.3, "Delayed Recalibration").

5.6.2 Configuration 2 - 44h

8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Bit 6 - BC_OUT_RECAL - Controls whether to retry analog calibration when the base count is out of limit for one or more sensor inputs.

 ‘0’ - When the BC_OUTx bit is set for a sensor input, the out of li mit base count will be used for

the sensor input.

 ‘1’ (default) - When the BC_OUTx bit is set for a sensor input (see Section 5.18, "Base Count Out

of Limit Register"), analog calibration will be repeated on the sensor input.

Bit 5 - BLK_PWR_CTRL - Determines whether the device will redu ce power consumption while waiting between conversion time completion and the end of the sensing cycle.

 ‘0’ (default) - The device will reduce power consumption during the ti me between the end of the

last conversion and the end of the sensing cycle.

 ‘1’ - The device will not reduce power consumption during the time between the end of the last

conversion and the end of the sensing cycle.

Bit 4 - BC_OUT_INT - Controls the interrupt behavior when the base count is out of limit for one or more sensor inputs.

 ‘0’ (default) - An interrupt is not generated when the BC_OUT bit is set (see Section 5.2 , "Status

Registers").

 ‘1’ - An interrupt is generated when the BC_OUT bit is set.

Bit 3 - SHOW_RF_NOISE - Determines whether the Noise Status bits will show RF Noise as the only input source.

 ‘0’ (default) - The Noise Status registers will show both RF noise and low frequency noise if either

is detected on a capacitive touch sensor input.

 ‘1’ - The Noise Status registers will only show RF noise if it is detected on a capacitive touch sensor

input. Low frequency noise will still be detected and touches will be blocked normally; however, the status bits will not be updated.

Bit 2 - DIS_RF_NOISE - Determines whether the RF noise filter is enabled. Se tting this bit disables the feature.

 ‘0’ (default) - If RF noise is detected by the analog block, the delta count o n the corresponding

channel is set to 0. Note that this does not require that Noi se Status bits be set.

 ‘1’ - A touch is not blocked even if RF noise is detected.

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Bit 1 - ACAL_FAIL_INT - Controls the interrupt behavior when analog calibration fails for one or more sensor inputs (see Section 4.4, "Sensor Input Calibration").

 ‘0’ (default) - An interrupt is not generated when the ACAL_FAIL bit is set (see Section 5.2, "Status

Registers").

 ‘1’ - An interrupt is generated when the ACAL_FAIL bit is set

Bit 0 - INT_REL_n - Controls the interrupt behavior when a release is detected on a button (see

Section 4.9.2, "Capacitive Sensor Input Interrupt Behavior").

 ‘0’ (default) - An interrupt is generated when a press is detected an d again when a release is

detected and at the repeat rate (if enabled - see Section 5.13).

 ‘1’ - An interrupt is generated when a press is detected and at the repeat rate but not when a

release is detected.

5.7 Sensor Input En able Register

Table 5.12 Sensor Input Enable Register

ADDRR/WREGISTERB7 B6B5B4B3B2B1B0DEFAULT

21h R/W

5.8 Sensor Input Configuration Register

Sensor Input

Enable

CS8_EN CS7_EN CS6_EN CS5_EN CS4_EN CS3_EN CS2_EN CS1_EN FFh

The Sensor Input Enable register determines whether a capacitive touch sensor input is incl uded in the sensing cycle in the Active state.

For all bits in this register:

 ‘0’ - The specified input is not included in the sensing cycle in the Active state.  ‘1’ (default) - The specified input is included in the sensing cycle in the Active state.

Bit 7 - CS8_EN - Determines whether the CS8 input is monitored in the Active state. Bit 6 - CS7_EN - Determines whether the CS7 input is monitored in the Active state. Bit 5 - CS6_EN - Determines whether the CS6 input is monitored in the Active state. Bit 4 - CS5_EN - Determines whether the CS5 input is monitored in the Active state. Bit 3 - CS4_EN - Determines whether the CS4 input is monitored in the Active state. Bit 2 - CS3_EN - Determines whether the CS3 input is monitored in the Active state. Bit 1 - CS2_EN - Determines whether the CS2 input is monitored in the Active state. Bit 0 - CS1_EN - Determines whether the CS1 input is monitored in the Active state.

Table 5.13 Sensor Input Configuration Register

ADDRR/W REGISTER B7 B6 B5B4B3B2B1B0DEFAULT

22h R/W

Sensor Input

Configuration

MAX_DUR[3:0] RPT_RATE[3:0] A4h

The Sensor Input Configuration Register controls timings associated with the capacitive sensor inputs.

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Bits 7 - 4 - MAX_DUR[3:0] - (default 1010b) - Determines the maximum time that a sensor pad is allowed to be touched until the capacitive touch sensor input is recalibrated (see Section 4.4.3,

"Delayed Recalibration"), as shown in Table 5.14.

Table 5.14 MAX_DUR Bit Decode

MAX_DUR[3:0]

TIME BEFORE RECALIBRATION32 1 0

0 0 0 0 560ms 0 0 0 1 840ms 0 0 1 0 1120ms 0 0 1 1 1400ms 0 1 0 0 1680ms 0 1 0 1 2240ms 0 1 1 0 2800ms 0 1 1 1 3360ms 1 0 0 0 3920ms 1 0 0 1 4480ms 1 0 1 0 5600ms (default) 1 0 1 1 6720ms 1 1 0 0 7840ms 1 1 0 1 8906ms 1 1 1 0 10080ms 1 1 1 1 11200ms

Bits 3 - 0 - RPT_RATE[3:0] - (default 0100b) Determines the time duration between interrupt assertions when auto repeat is enabled (see Section 4.9.2, "Capacitive Sensor Input Interrupt Behavior"). The resolution is 35ms and the range is from 35ms to 560ms as shown in Table 5.15.

Table 5.15 RPT_RATE Bit Decode

RPT_RATE[3:0]

INTERRUPT REPEAT RATE3210

0000 35ms 0001 70ms 0 0 1 0 105ms 0 0 1 1 140ms 0 1 0 0 17 5ms (default)

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Table 5.15 RPT_RATE Bit Decode (continued)

RPT_RATE[3:0]

0 1 0 1 210ms 0 1 1 0 245ms 0 1 1 1 280ms 1 0 0 0 315ms 1 0 0 1 350ms 1 0 1 0 385ms 1 0 1 1 420ms 1 1 0 0 455ms 1 1 0 1 490ms 1 1 1 0 525ms

INTERRUPT REPEAT RATE3210

1 1 1 1 560ms

5.9 Sensor Input Configuration 2 Register

Table 5.16 Sensor Input Configuration 2 Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

23h R/W

Sensor Input

Configuration 2

- - - - M_PRESS[3:0] 07h

Bits 3 - 0 - M_PRESS[3:0] - (default 0111b) - Determines the minimum amount of time that sensor inputs configured to use auto repeat must detect a sensor pad touch to detect a “press and hold” event (see Section 4.9.2, "Capacitive Sensor Input Interrupt Behavi or"). If the sensor input detects a touch for longer than the M_PRESS[3:0] settings, a “press and hold” event is detected. If a sensor input detects a touch for less than or equal to the M_PRESS[3:0] settings, a touch event is detected.

The resolution is 35ms and the range is from 35ms to 560ms as shown in Table 5.17.

Table 5.17 M_PRESS Bit Decode

M_PRESS[3:0]

M_PRESS SETTINGS3210

0000 35ms 0001 70ms 0 0 1 0 105ms 0 0 1 1 140ms

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Table 5.17 M_PRESS Bit Decode (continued)

M_PRESS[3:0]

M_PRESS SETTINGS3210

0 1 0 0 175ms 0 1 0 1 210ms 0 1 1 0 245ms 0 1 1 1 28 0ms (default) 1 0 0 0 315ms 1 0 0 1 350ms 1 0 1 0 385ms 1 0 1 1 420ms 1 1 0 0 455ms 1 1 0 1 490ms

Datasheet

1 1 1 0 525ms 1 1 1 1 560ms

5.10 Averaging and Sampling Configuration Register

Table 5.18 Averaging and Sampling Configuration Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

24h R/W

Averaging and

Sampling

Config

The Averaging and Sampling Configuration register controls the number of samples taken and the target sensing cycle time for sensor inputs enabled in the Active state.

Bits 6 - 4 - AVG[2:0] - Determines the number of samples that are taken for all channels enabled in the Active state during the sensing cycle as shown in Table 5.19. All samples are taken consecutively on the same channel before the next channel is sampled and the result is ave raged over the number of samples measured before updating the measured results.

For example, if CS1, CS2, and CS3 are sampled during the sensing cycle, and the AVG[2:0] bits are set to take 4 samples per channel, then the full sensing cycle will be: CS1, CS1, CS1, CS1, CS2, CS2, CS2, CS2, CS3, CS3, CS3, CS3.

- AVG[2:0] SAMP_TIME[1:0]

CYCLE_TIME

[1:0]

39h

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Table 5.19 AVG Bit Decode

AVG[2:0]

000 1 001 2 010 4 0 1 1 8 (default) 100 16 101 32 110 64 1 1 1 128

NUMBER OF SAMPLES TAKEN

PER MEASUREMENT210

Bits 3 - 2 - SAMP_TIME[1:0] - Determines the time to take a single sample as shown in Table 5.20. Sample time affects the magnitude of the base counts, as shown in Table4.1, "Ideal Base Counts".

Table 5.20 SAMP_TIME Bit Decode

SAMP_TIME[1:0]

SAMPLE TIME10

0 0 320us 0 1 640us 1 0 1.28ms (default) 1 1 2.56ms

Bits 1 - 0 - CYCLE_TIME[1:0] - Determines the desired sensing cycle time for channels enabled in the Active state, as shown in Table 5.21. All enabled channel s are sampl ed at the beginnin g of the sensing cycle. If additional time is remaining, the device is placed into a lower power state for the remainder of the sensing cycle.

Table 5.21 CYCLE_TIME Bit Decode

CYCLE_TIME[1:0]

PROGRAMMED SENSING CYCLE

TIME10

00 35ms 0 1 70ms (default) 1 0 105ms 1 1 140ms

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APPLICATION NOTE: The programmed sensing cycle time (CYCLE_TIME[1:0]) is only maintained if the actual time

to take the samples is less than the programmed cycle time. The AVG[2:0] bits will take priority, so the sensing cycle time will be extended as necessary to accommodate the number of samples to be measured.

5.11 Calibration Activate and Status Register

Table 5.22 Calibration Activate and Status Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

26h R/W

Calibration

Activate

and Status

CS8_

CAL

CS7_

CAL

CS6_

CAL

CS5_

CAL

CS4_

CAL

CS3_

CAL

CS2_

CAL

CS1_

CAL

00h

The Calibration Activate and Status Register serves a dual function:

1. It forces the selected sensor inputs to be calibrated, affecting both the analog and digital blocks (see Section 4.4, "Senso r Input Calibration"). When one or more bits are set, the device performs the calibration routine on the correspond ing sensor inputs. When the analog calibration routine is finished, the CALX[9:0] bits are updated (see Section 5.29, "Sensor Input Calibration Registers"). If the analog calibration routine completed successfully for a sensor input, the corresponding bit is automatically cleared.

APPLICATION NOTE: In the case above, bits can be set by host or are automatically set by the d evice whenever

a sensor input is newly enabled (such as coming out of Deep Sleep, after power-on reset, when a bit is set in the Sensor Enable Channel Enable register (21h) and the device is in the Active state, or when a bit is set in the Standby Channel Enable Register (40h) and the device is in the Standby state).

2. It serves as an indicator of an analog calibration failure. If any of the bits could not be cleared, the ACAL_FAIL bit is set (see Section 5.2, "Status Registers"). A bit will fail to clear if a noise bit is set or if the calibration value is at the maximum or minimum value.

APPLICATION NOTE: In the case above, do not check the Calibration Activate and Status bits for failures unless

the ACAL_FAIL bit is set. In addition, if a sensor input is newly enabled, do not check the Calibration Activate and Status bits until time has elapsed to complete calibration on the sensor input. Otherwise, the ACAL_FAIL bit may be set for one sensor input, but the newly enabled sensor input may still be set to ‘1’ in the Calibration Activate and Status, not because it failed, but because it has not been calibrated yet.

For all bits in this register:

 ‘0’ - No action needed.  ‘1’ - Writing a ‘1’, forces a calibration on the corresponding sensor input. If the ACAL_FAIL flag is

set and this bit is set (see application note above), the sensor input cou ld not complete analog

calibration. Bit 7 - CS8_CAL - Bit for CS8 input. Bit 6 - CS7_CAL - Bit for CS7 input. Bit 5 - CS6_CAL - Bit for CS6 input. Bit 4 - CS5_CAL - Bit for CS5 input. Bit 3 - CS4_CAL - Bit for CS4 input. Bit 2 - CS3_CAL - Bit for CS3 input.

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Bit 1 - CS2_CAL - Bit for CS2 input. Bit 0 - CS1_CAL - Bit for CS1 input.

APPLICATION NOTE: Writing a ‘0’ to clear a ‘1’ may cause a planned calibrati on to be skipped, if the calibration

routine had not reached the sensor input yet.

5.12 Interrupt Enable Register

Table 5.23 Interrupt Enable Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

27h R/W

Interrupt

Enable

CS8_

INT_EN

CS7_

INT_EN

CS6_

INT_EN

CS5_

INT_EN

CS4_

INT_EN

CS3_

INT_EN

CS2_

INT_EN

CS1_

INT_EN

The Interrupt Enable register determines whether a sensor pad touch or release (if enabled) causes an interrupt (see Section 4.9, "Interrupts").

For all bits in this register:

 ‘0’ - The ALERT# pin will not be asserted if a touch is detected on the specified sensor input.  ‘1’ (default) - The ALERT# pin will be asserted if a touch is detected on the specified sensor input.

Bit 7 - CS8_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS8 (associated with the CS8 status bit).

Bit 6 - CS7_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS7 (associated with the CS7 status bit).

Bit 5 - CS6_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS6 (associated with the CS6 status bit).

Bit 4 - CS5_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS5 (associated with the CS5 status bit).

Bit 3 - CS4_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS4 (associated with the CS4 status bit).

Bit 2 - CS3_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS3 (associated with the CS3 status bit).

FFh

Bit 1 - CS2_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS2 (associated with the CS2 status bit).

Bit 0 - CS1_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS1 (associated with the CS1 status bit).

5.13 Repeat Rate Enable Register

Table 5.24 Repeat Rate Enable Register

ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT

28h R/W

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Repeat Rate

Enable

CS8_

RPT_EN

CS7_

RPT_EN

CS6_

RPT_EN

CS5_

RPT_EN

CS4_

RPT_EN

CS3_

RPT_EN

CS2_

RPT_EN

CS1_

RPT_EN

FFh

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The Repeat Rate Enable register enables the repeat rate of the sensor inpu ts as described in Section

4.9.2, "Capacitive Sensor Input Interrupt Behavior".

For all bits in this register:

 ‘0’ - The repeat rate for the specified sensor input is disabled. It will only generate an interrupt when

a touch is detected and when a release is detected (if enabled) n o matter how long the touch is

held.

 ‘1’ (default) - The repeat rate for the speci fied sensor input is enabled. In the case of a “touch”

event, it will generate an interrupt when a touch is detected and a release is detected (as

determined by the INT_REL_n bit - see Section 5.6, "Configuration Registers"). In the case of a

“press and hold” event, it will generate a n interrupt when a tou ch is detected and at the repeat rate

so long as the touch is held. Bit 7 - CS8_RPT_EN - Enables the repeat rate for capacitive touch sensor input 8. Bit 6 - CS7_RPT_EN - Enables the repeat rate for capacitive touch sensor input 7. Bit 5 - CS6_RPT_EN - Enables the repeat rate for capacitive touch sensor input 6. Bit 4 - CS5_RPT_EN - Enables the repeat rate for capacitive touch sensor input 5. Bit 3 - CS4_RPT_EN - Enables the repeat rate for capacitive touch sensor input 4. Bit 2 - CS3_RPT_EN - Enables the repeat rate for capacitive touch sensor input 3. Bit 1 - CS2_RPT_EN - Enables the repeat rate for capacitive touch sensor input 2. Bit 0 - CS1_RPT_EN - Enables the repeat rate for capacitive touch sensor input 1.

5.14 Signal Guard Enable Register

T able 5.25 Signal Guard Enable Register

ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT

29h R/W

Signal Guard

Enable

The Signal Guard Enable register enables the signal gua rd for the specified senso r inpu ts as described in Section 4.5.1, "Signal Guard". When the signa l guard is enabled, CS5 is disabled.

For all bits in this register:

 ‘0’ (default) - The signal guard is disabled for the specified sensor input.  ‘1’ - The signal guard is enabled for the specified sensor input.

Bit 7 - CS8_SG_EN - Enables the signal guard for capacitive touch sensor input 8. Bit 6 - CS7_SG_EN - Enables the signal guard for capacitive touch sensor input 7.

CS8_

SG_EN

CS7_

SG_EN

CS6_

SG_EN

CS4_

SG_EN

CS3_

SG_EN

CS2_

SG_EN

CS1_

SG_EN

00h

Bit 5 - CS6_SG_EN - Enables the signal guard for capacitive touch sensor input 6. Bit 3 - CS4_SG_EN - Enables the signal guard for capacitive touch sensor input 4. Bit 2 - CS3_SG_EN - Enables the signal guard for capacitive touch sensor input 3. Bit 1 - CS2_SG_EN - Enables the signal guard for capacitive touch sensor input 2. Bit 0 - CS1_SG_EN - Enables the signal guard for capacitive touch sensor input 1.

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5.15 Multiple Touch Configuration Register

Table 5.26 Multiple Touch Configuration

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

2Ah R/W

Multiple T ouc h

Config

MULT_

BLK_

- - - B_MULT_T[1:0] - - 80h

The Multiple Touch Configuration register controls the settings for the multiple touch dete ction circuitry. These settings determine the number of simultaneous buttons that may be pressed be fore additional buttons are blocked and the MULT status bit is set.

Bit 7 - MULT_BLK_EN - Enables the multiple button blocking circuitry.

 ‘0’ - The multiple touch circuitry is disabled. The device will no t block multiple touches.  ‘1’ (default) - The multiple touch circuitry is enabled . The device will flag the number of touches

equal to programmed multiple touch threshold and block al l others. It will remember which sensor

inputs are valid and block all others until that sensor pad has been released. Once a sensor pad

has been released, the N detected touches (determined via the sensing cycle order of CS1 - CS8)

will be flagged and all others blocked. Bits 3 - 2 - B_MULT_T[1:0] - Determines the number of simultaneous touches on all sensor pads

before a Multiple Touch Event is detected and sen sor inputs are blocked. The bit decode is given by

Table 5.27.

Table 5.27 B_MULT_T Bit Decode

B_MULT_T[1:0]

NUMBER OF SIMULTANEOUS TOUCHES10

0 0 1 (default) 01 2 10 3 11 4

5.16 Multiple Touch Pattern Configuration Register

Table 5.28 Multiple Touch Pattern Configuration

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

2Bh R/W

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Multiple T ouch Pattern Config

MTP_ EN - - - MTP_TH[1:0]

COMP_

PTRN

MTP_

ALERT

00h

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The Multiple Touch Pattern Configuration register controls the settings for the multiple touch pattern detection circuitry. This circuitry works like the multiple touch detection circuitry with the following differences:

1. The detection threshold is a percentage of the touch detection threshold as defined by the

MTP_TH[1:0] bits whereas the multiple touch circuitry uses the touch detection threshold.

2. The MTP detection circuitry either will detect a specific pattern of sensor inputs as determined by

the Multiple Touch Pattern register settings or it will use the Multiple Touch Pattern register settings to determine a minimum number of sensor inputs that will cause the MTP circuitry to flag an event (see Section 5.17, "Multiple Touch Pattern Register"). When using pattern recognition mode, if all of the sensor inputs set by the Multiple Touch Pattern register have a delta count greater than the MTP threshold or have their corresponding Noise Flag Status bits set, the MTP bit will be set. When using the absolute number mode, if the number of sensor inputs with thresholds above the MTP threshold or with Noise Flag Status bits set is equal to or greater than this number, the MTP bit will be set.

3. When an MTP event occurs, all touches are blocked and an interrupt is generated.

4. All sensor inputs will remain blocked so long as the requisite number of sensor inputs are above

the MTP threshold or have Noise Flag Status bits set. Once this condition is removed, touch detection will be restored. Note that the MTP status bit is only cleared by writing a ‘0’ to the INT bit once the condition has been removed.

Bit 7 - MTP_EN - Enables the multiple touch pattern detection circuitry.

 ‘0’ (default) - The MTP detection circuitry is disabled.  ‘1’ - The MTP detection circuitry is enabled.

Bits 3 - 2 - MTP_TH[1:0] - Determine the MTP threshold, as shown in Table 5.29. This threshold is a percentage of sensor input threshold (see Section 5.20, "Sensor In put Threshold Registers") for inputs enabled in the Active state or of the standby threshold (see Section 5.25, "Standby Threshold

Table 5.29 MTP_TH Bit Decode

MTP_TH[1:0]

THRESHOLD DIVIDE SETTING10

0 0 12.5% (default) 0125% 1 0 37.5% 1 1 100%

Bit 1 - COMP_PTRN - Determines whether the MTP detection circuitry will use the Multiple Touch Pattern register as a specific pattern of sensor inputs or as an absolute number of sensor inputs.

 ‘0’ (default) - The MTP detection circuitry will use the Multiple Touch Pattern register bit settings as

an absolute minimum number of sensor inputs that must be above the threshold or have Noise

Flag Status bits set. The number will be equal to the number of bits set in the register.

 ‘1’ - The MTP detection circuitry will use pattern recognition. Each bit set in the Multiple Touch

Pattern register indicates a specific sensor input that must have a delta count greater than the MTP

threshold or have a Noise Flag Status bit set. If the criteria are met, the MTP status bit will be set.

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Bit 0 - MTP_ALERT - Enables an interrupt if an MTP event occurs. In either condition, the MTP status bit will be set.

 ‘0’ (default) - If an MTP event occurs, the ALERT# pin is not asserted.  ‘1’ - If an MTP event occurs, the ALERT# pin will be asserted.

5.17 Multiple To uch Pattern Register

Table 5.30 Multiple Touch Pattern Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

2Dh R/W

Multiple

Touch

Pattern

CS8_

PTRN

CS7_

PTRN

CS6_ PTRN

CS5_

PTRN

CS4_

PTRN

CS3_

PTRN

CS2_ PTRN

CS1_

PTRN

FFh

The Multiple Touch Pattern register acts as a pattern to identify an expected sensor input profile for diagnostics or other significant events. There are two methods for how the Multiple Touch Pattern register is used: as specific sensor inputs or number of sensor input that must exceed the MTP threshold or have Noise Flag Status bits set. Which method is used is based on the COMP_PTRN bit (see Section 5.16). The methods are described below.

1. Specific Sensor Inputs: If, during a single sensing cycle, the specific sensor inputs above the MTP

threshold or with Noise Flag Status bits set match those bits set in the Multiple Touch Pattern register, an MTP event is flagged.

2. Number of Sensor Inputs: If, during a single sensing cycle, the number of sensor inputs with a delta

count above the MTP threshold or with Noise Flag Status bits set is equal to or greater than the number of pattern bits set, an MTP event is flagged.

For all bits in this register:

 ‘0’ - The specified sensor input is not considered a part of the pattern.  ‘1’ - The specified sensor input is considered a part of the pattern, or the absolute number of sensor

inputs that must have a delta count greater than the MTP threshold or have the Noise Flag Status

bit set is increased by 1. Bit 7 - CS8_PTRN - Determines whether CS8 is considered as part of the Multiple Touch Pattern. Bit 6 - CS7_PTRN - Determines whether CS7 is considered as part of the Multiple Touch Pattern. Bit 5 - CS6_PTRN - Determines whether CS6 is considered as part of the Multiple Touch Pattern. Bit 4 - CS5_PTRN - Determines whether CS5 is considered as part of the Multiple Touch Pattern. Bit 3 - CS4_PTRN - Determines whether CS4 is considered as part of the Multiple Touch Pattern. Bit 2 - CS3_PTRN - Determines whether CS3 is considered as part of the Multiple Touch Pattern. Bit 1 - CS2_PTRN - Determines whether CS2 is considered as part of the Multiple Touch Pattern. Bit 0 - CS1_PTRN - Determines whether CS1 is considered as part of the Multiple Touch Pattern.

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5.18 Base Count Out of Limit Register

Table 5.31 Base Count Out of Limit Register

Datasheet

ADDRR/WREGISTERB7B6B5B4B3B2B1B0

2Eh R

Base Count Out of Limit

BC_

OUT_

BC_

OUT_

BC_

OUT_

BC_

OUT_

BC_

OUT_

BC_

OUT_

BC_

OUT_

BC_

OUT_

The Base Count Out of Limit Register indicates which sensor inputs have base counts out of limit (see

Section 4.4, "Sensor Input Calibration"). When these bits are set, the BC_OUT bit is set (see Section

5.2, "Status Registers").

For all bits in this register:

 ‘0’ - The base count for the specified sensor input is in the ope rating range.  ‘1’ - The base count of the specified sensor input is not in the operating range.

Bit 7 - BC_OUT_8 - Indicates whether CS8 has a base count out of limit. Bit 6 - BC_OUT_7 - Indicates whether CS7 has a base count out of limit. Bit 5 - BC_OUT_6 - Indicates whether CS6 has a base count out of limit. Bit 4 - BC_OUT_5 - Indicates whether CS6 has a base count out of limit. Bit 3 - BC_OUT_4 - Indicates whether CS6 has a base count out of limit. Bit 2 - BC_OUT_3 - Indicates whether CS3 has a base count out of limit. Bit 1 - BC_OUT_2 - Indicates whether CS2 has a base count out of limit.

DEFAULT

00h

Bit 0 - BC_OUT_1 - Indicates whether CS1 has a base count out of limit.

5.19 Recalibration Configuration Register

Ta ble 5.32 Recalibration Configuration Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

2Fh R/W

Recalibration

Configuration

The Recalibration Configuration register con trols some recalibration routine settings (see Sectio n 4.4,

"Sensor Input Calibration") as well as advanced controls to program the Sensor Input Threshold

Input 1 Threshold register.

 ‘0’ - Each Sensor Input X Threshold register is updated individually.  ‘1’ (default) - Writing the Sensor Input 1 Threshold register will automatically over write the Sensor

Input Threshold registers for all sensor inputs (Sensor Input Threshold 1 through Sen sor Input

Threshold 8). The individual Sensor Input X Threshold registers (Sensor Input 2 T hreshold through

Sensor Input 8 Threshold) can be individually updated at any time.

BUT_

LD_TH

NO_CLR

_INTD

NO_CLR

_NEG

NEG_DELTA_

CNT[1:0]

CAL_CFG[2:0] 8Ah

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Bit 6 - NO_CLR_INTD - Controls whether the accumulation of intermediate data is cleared if the noise status bit is set.

 ‘0’ (default) - The accumulation of intermediate data is cleared if the noise status bit is set.  ‘1’ - The accumulation of intermediate data is not cleared if the noise status bit is set.

APPLICATION NOTE: Bits 5 and 6 should both be set to the same value. Either both should be set to ‘ 0’ or both

should be set to ‘1’.

Bit 5 - NO_CLR_NEG - Controls whether the consecutive negative delta counts counter is cleared if the noise status bit is set.

 ‘0’ (default) - The consecutive negative delta counts counter is cleared if the noise status bit is set.  ‘1’ - The consecutive negative delta counts counter is not cleared if the noise status bit is set.

Bits 4 - 3 - NEG_DELTA_CNT[1:0] - Determines the number of negative delta counts necessary to trigger a digital recalibration (see Section 4.4.2, "Negative Delta Count Recalibration"), as shown in

Table 5.33.

Table 5.33 NEG_DELTA_CNT Bit Decode

NEG_DELTA_CNT[1:0]

NUMBER OF CONSECUTIVE NEGATIVE DELTA

COUNT VALUES10

00 8 0 1 16 (default) 10 32 1 1 None (disabled)

Bits 2 - 0 - CAL_CFG[2:0] - Determines the update time and number of samples of the automatic recalibration routine (see Section 4.4.1, "Automatic Recalibration"). The settings apply to all sensor inputs universally (though individual sensor inputs can be configured to support recalibration - see

Section 5.11).

Table 5.34 CAL_CFG Bit Decode

CAL_CFG[2:0]

RECALIBRATION

SAMPLES (SEE

Note 5.1)

UPDATE TIME (SEE

Note 5.2)210

0 0 0 16 16 001 32 32 0 1 0 64 64 (default) 0 1 1 128 128 100 256 256 1 0 1 256 1024 1 1 0 256 2048 1 1 1 256 4096

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Note 5.1 Recalibration Samples refers to the number of samples that are measured and averaged

before the Base Count is updated however does not control the base count u pda te peri od.

Note 5.2 Update Time refers to the amount of time (in sensing cycle periods) that elapses before

the Base Count is updated. The time will depend upon the number of channels enabled, the averaging setting, and the programmed sensing cycle time.

5.20 Sensor Input Threshold Registers

Table 5.35 Sensor Input Threshold Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

30h R/W

31h R/W

32h R/W

33h R/W

34h R/W

35h R/W

36h R/W

37h R/W

Sensor Input 1

Threshold

Sensor Input 2

Threshold

Sensor Input 3

Threshold

Sensor Input 4

Threshold

Sensor Input 5

Threshold

Sensor Input 6

Threshold

Sensor Input 7

Threshold

Sensor Input 8

Threshold

The Sensor Input Threshold registers store the delta threshold that is used to determine if a touch has been detected. When a touch occurs, the input signal of the corresponding sensor pad chang es due to the capacitance associated with a touch. If the sensor input change excee ds the threshold settings, a touch is detected.

-6432168421 40h

When the BUT_LD_TH bit is set (see Section 5.19 - bit 7), writi ng data to the Sen sor Input 1 Threshold register will update all of the Sensor Input Threshold registers (31h - 37h inclusive).

5.21 Sensor Input Noise Threshold Register

Table 5.36 Sensor Input Noise Threshold Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

38h R/W

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Sensor Input

Noise Threshold

The Sensor Input Noise Threshold register controls the value of a secondary internal threshold to detect noise and improve the automatic recalibration routine. If a capacitive touch sensor input exceeds the Sensor Input Noise Threshold but does not exceed the sensor input threshold, it is determined to

------

CS_BN_TH

[1:0]

01h

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be caused by a noise spike. That sample is not used by the automatic recalibration routine. This feature can be disabled by setting the DIS_DIG_NOISE bit.

Bits 1-0 - CS1_BN_TH[1:0] - Controls the noise threshold for all capacitive touch sensor inputs, as shown in Table 5.37. The threshold is proportion al to the threshold setting.

Table 5.37 CSx_BN_TH Bit Decode

CS_BN_TH[1:0]

0025% 0 1 37.5% (default) 1050% 1 1 62.5%

5.22 Standby Channel Register

PERCENT THRESHOLD SETTING10

T able 5.38 Standby Channel Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

40h R/W

Standby

Channel

CS8_ STBY

CS7_

STBY

CS6_ STBY

CS5_

STBY

CS4_ STBY

CS3_

STBY

CS2_

STBY

CS1_

STBY

00h

The Standby Channel register controls which (if any) capacitive touch sensor inputs are enabled in Standby (see Section 4.3.1.2, "Standby State Sensing Settings").

For all bits in this register:

 ‘0’ (default) - The specified channel will not be monitored in Standby.  ‘1’ - The specified channel will be monitored in Standby. It will use the standby threshold setting,

and the standby averaging and sensitivity settings. Bit 7 - CS8_STBY - Controls whether the CS8 channel is enabled in Standby. Bit 6 - CS7_STBY - Controls whether the CS7 channel is enabled in Standby. Bit 5 - CS6_STBY - Controls whether the CS6 channel is enabled in Standby. Bit 4 - CS5_STBY - Controls whether the CS5 channel is enabled in Standby. Bit 3 - CS4_STBY - Controls whether the CS4 channel is enabled in Standby. Bit 2 - CS3_STBY - Controls whether the CS3 channel is enabled in Standby. Bit 1 - CS2_STBY - Controls whether the CS2 channel is enabled in Standby. Bit 0 - CS1_STBY - Controls whether the CS1 channel is enabled in Standby.

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5.23 Standby Configuration Register

Table 5.39 Standby Configuration Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

41h R/W

Standby

Configuration

AVG_

SUM

STBY_AVG[2:0]

STBY_SAMP_

TIME[1:0]

STBY_CY_TIME

[1:0]

The Standby Configuration register controls averaging and sensing cycle time for sensor inputs enabled in Standby. This register allows the user to change averaging and sample time s on a limited number of sensor inputs in Standby and still maintain normal functionality in the Active state.

Bit 7 - AVG_SUM - Determines whether the sensor inputs enabled in Standby will average the programmed number of samples or whether they will accumulate for the programmed number of samples.

 ‘0’ - (default) - The Standby enabled sensor input delta count values will be based on the average

of the programmed number of samples when compared against the threshold.

 ‘1’ - The Standby enabled sensor input delta count values will be based on the summation of the

programmed number of samples when compared against the threshold. Caution should be used

with this setting as a touch may overflow the delta count registers and may result in false readings. Bits 6 - 4 - STBY_AVG[2:0] - Determines the number of samples that are taken for all Standby enabled

channels during the sensing cycle as shown in Table 5.40. All samples are taken consecutively on the same channel before the next channel is sampled and the result is averaged over the number of samples measured before updating the measured results.

Table 5.40 STBY_AVG Bit Decode

STBY_AVG[2:0]

NUMBER OF SAMPLES TAKEN

PER MEASUREMENT210

39h

000 1 001 2 010 4 0 1 1 8 (default) 100 16 101 32 110 64 1 1 1 128

Bit 3 - 2 - STBY_SAMP_TIME[1:0] - Determines the time to take a single sample for sensor inputs enabled in Standby as shown in Table 5.41.

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Table 5.41 STBY_SAMP_TIME Bit Decode

STBY_SAMP_TIME[1:0]

0 0 320us 0 1 640us 1 0 1.28ms (default) 1 1 2.56ms

Bits 1 - 0 - STBY_CY_TIME[2:0] - Determines the desired sensing cycle time for sensor inputs enabled during Standby, as shown in Table 5.42. This control is also used to determine p rogrammed cycle time in the Combo state (see Section 4.3.1.3, "Combo State Sensing Settings"). All enabled channels are sampled at the beginning of the sensing cycle. If additional time is remaining, the device is placed into a lower power state for the remainder of the sensing cycle.

SAMPLING TIME10

Table 5.42 STBY_CY_TIME Bit Decode

STBY_CY_TIME[1:0]

PROGRAMMED SENSING CYCLE

TIME10

00 35ms 0 1 70ms (default) 1 0 105ms 1 1 140ms

APPLICATION NOTE: The programmed sensing cycle time (STDBY_CY_TIME[1:0] is only maintained if the actual

time to take the samples is less than the p rogrammed cycle time. The STBY_AVG[2:0] bits will take priority, so the sensing cycle time will be extended as necessary to accommodate the number of samples to be measured.

5.24 Standby Sensitivity Register

Table 5.43 Standby Sensitivity Register

ADDRR/WREGISTER B7 B6B5B4B3B2B1B0DEFAULT

42h R/W

Standby

Sensitivity

- - - - - STBY_SENSE[2:0] 02h

The Standby Sensitivity register controls the sensitivity for sensor inputs enabled in Standby. Bits 2 - 0 - STBY_SENSE[2:0] - Controls the sensitivity for sensor inputs that are enabled in Standby.

The sensitivity settings act to scale the relative delta count value higher or lower based on the system parameters. A setting of 000b is the most sensitive while a setting of 111b i s the least sensitive. At the more sensitive settings, touches are detected for a smaller delta capacitance corresponding to a

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Datasheet

“lighter” touch. These settings are more sensitive to noise, however, and a noisy environment may flag more false touches than higher sensitivity levels.

APPLICATION NOTE: A value of 128x is the most sensitive setting available. At the most sensitivity settings, the

MSB of the Delta Count register represents 64 out of ~25,000 which co rresponds to a touch of approximately 0.25% of the base capacitance (or a capacitance). Conversely a value of 1x is the least sensitive setting available. At these settings, the MSB of the Delta Count register corresponds to a delta count of 8192 counts out of ~25,000 which corresponds to a touch of approximately 33% of the base capacitance

ΔC of 3.33pF from a 10pF base capacitance).

(or a

Table 5.44 STBY_SENSE Bit Decode

STBY_SENSE[2:0]

0 0 0 128x (most sensitive) 001 64x 0 1 0 32x (default)

ΔC of 25fF from a 10pF base

SENSITIVITY MULTIPLIER210

011 16x 100 8x 101 4x 110 2x 1 1 1 1x - (least sensitive)

5.25 Standby Threshold Register

Table 5.45 Standby Threshold Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

43h R/W

Standby

Threshold

The Standby Threshold register stores the delta threshold that is used to determine if a touch has been detected. When a touch occurs, the input signal of the corresponding sensor pad changes due to the capacitance associated with a touch. If the sensor input change exceeds the threshold settings, a touch is detected.

-6432168421 40h

5.26 Sensor Input Base Count Registers

Table 5.46 Sensor Input Base Count Registers

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

50h R

DS01571A-page 56  2013 Microchip Technology Inc.

Sensor Input 1

Base Count

128 64 32 16 8 4 2 1 C8h

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Datasheet

Table 5.46 Sensor Input Base Count Registers (continued)

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

51h R

52h R

53h R

54h R

55h R

56h R

57h R

Sensor Input 2

Base Count

Sensor Input 3

Base Count

Sensor Input 4

Base Count

Sensor Input 5

Base Count

Sensor Input 6

Base Count

Sensor Input 7

Base Count

Sensor Input 8

Base Count

128 64 32 16 8 4 2 1 C8h

The Sensor Input Base Count registers store the calibrated “not touched” input value from the capacitive touch sensor inputs. These registers are periodically updated by the calibration and recalibration routines.

The routine uses an internal adder to add the current count value for each readin g to the sum of the previous readings until sample size has been reac hed. At this point, the upper 16 bits are taken and used as the Sensor Input Base Count. The internal adder is then reset and the reca libration routine continues.

The data presented is determined by the BASE_SHIFT[3:0] bits (see Section 5.5).

5.27 Power Button Register

Table 5.47 Power Button Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

60h R/W Power Button - - - - - PWR_BTN[2:0] 0 0h

The Power Button Register indicates the sensor input that has been designated as the p ower button (see Section 4.6, "Power Button").

Bits 2 - 0 - PWR_BTN[2:0] - When the power button feature is enabled, this control indicates the sensor input to be used as the power button. The decode is shown in Table 5.48.

Table 5.48 PWR_BTN Bit Decode

PWR_BTN[3:0]

SENSOR INPUT DESIGNATED AS POWER BUTTON201

000 CS1 001 CS2

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Table 5.48 PWR_BTN Bit Decode (continued)

PWR_BTN[3:0]

SENSOR INPUT DESIGNATED AS POWER BUTTON201

010 CS3 011 CS4 100 CS5 101 CS6 110 CS7 111 CS8

5.28 Power Button Configuration Register

Table 5.49 Power Button Configuration Register

Datasheet

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

STBY_

PWR_

STBY_PWR_

TIME [1:0]

PWR_

PWR_TIME [1:0] 22h

61h R/W

Power Button

Configuration

The Power Button Configuration Register controls the length of time that the designate d power button must indicate a touch before an interrupt is generated and the power status indicator is set (see

Section 4.6, "Power Button").

Bit 6 - STBY_PWR_EN - Enables the power button feature in the Standby state.

 ‘0’ (default) - The Standby power button circuitry is disabled.  ‘1’ - The Standby power button circuitry is enabled.

Bits 5 - 4 - STBY_PWR_TIME[1:0] - Determines the overall time, as shown in Table 5.50, that the power button must be held in the Standby state, in order for an interrupt to be generated and the PWR bit to be set.

Bit 2 - PWR_EN - Enables the power button feature in the Acti ve state.

 ‘0’ (default) - The power button circuitry is disabled in the Active state.  ‘1’ -The power button circuitry is enabled in the Active state.

Bits 1 - 0 - PWR_TIME[1:0] - Determines the overall time, as shown in Table 5.50, that the power button must be held in the Active state, in order for an interrupt to be generated and the PWR bit to be set.

Table 5.50 Power Button Time Bits Decode

PWR_TIME[1:0] / STBY_PWR_TIME[1:0]

POWER BUTTON TOUCH HOLD TIME10

0 0 280ms

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Datasheet

Ta ble 5.50 Power Button Time Bits Decode (continued)

PWR_TIME[1:0] / STBY_PWR_TIME[1:0]

POWER BUTTON TOUCH HOLD TIME10

0 1 560ms 1 0 1.12 sec (default) 1 1 2.24 sec

5.29 Sensor Input Calibration Registers

Table 5.51 Sensor Input Calibration Registers

ADDR REGISTER R/W B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

B1h

B2h

B3h

B4h

B5h

B6h

B7h

B8h

B9h

BAh

Sensor Input 1

Calibration

Sensor Input 2

Calibration

Sensor Input 3

Calibration

Sensor Input 4

Calibration

Sensor Input 5

Calibration

Sensor Input 6

Calibration

Sensor Input 7

Calibration

Sensor Input 8

Calibration

Sensor Input

Calibration

LSB 1

Sensor Input

Calibration

LSB 2

R CAL1_9 CAL1_8 CAL1_7 CAL1_6 CAL1_5 CAL1_4 CAL1_3 CAL1_2 00h

R CAL2_9 CAL2_8 CAL2_7 CAL2_6 CAL2_5 CAL2_4 CAL2_3 CAL2_2 00h

R CAL3_9 CAL3_8 CAL3_7 CAL3_6 CAL3_5 CAL3_4 CAL3_3 CAL3_2 00h

R CAL4_9 CAL4_8 CAL4_7 CAL4_6 CAL4_5 CAL4_4 CAL4_3 CAL4_2 00h

R CAL5_9 CAL5_8 CAL5_7 CAL5_6 CAL5_5 CAL5_4 CAL5_3 CAL5_2 00h

R CAL6_9 CAL6_8 CAL6_7 CAL6_6 CAL6_5 CAL6_4 CAL6_3 CAL6_2 00h

R CAL7_9 CAL7_8 CAL7_7 CAL7_6 CAL7_5 CAL7_4 CAL7_3 CAL7_2 00h

R CAL8_9 CAL8_8 CAL8_7 CAL8_6 CAL8_5 CAL8_4 CAL8_3 CAL8_2 00h

R CAL4_1 CAL4_0 CAL3_1 CAL3_0 CAL2_1 CAL2_0 CAL1_1 CAL1_0 00h

R CAL8_1 CAL8_0 CAL7_1 CAL7_0 CAL6_1 CAL6_0 CAL5_1 CAL5_0 00h

The Sensor Input Calibration registers hold the 10-bit value that represents the last calibration value. The value represents the capacitance applied to the internal sensing circuits to balance the capacitance of the sensor input pad. Minimum (000h) and maximum (3FFh) values indicate analog calibration failure (see Section 4.4, "Sensor Input Calibration").

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

5.30 Calibration Sensitivity Configuration Registers

Table 5.52 Calibration Sensitivity Configuration Registers

Datasheet

ADDR REGISTER R/W B7 B6 B5 B4 B3 B2 B1 B0

80h

81h

Calibration

Sensitivity

Config 1

Calibration

Sensitivity

Config 2

CALSENx[1:0] - Controls the gain used by the calibration routine to enable sensor inputs to be more sensitive for proximity detection. Gain is based on capacitance touch pad capacitance ranges, as shown in Table 5.53. Since each sensor input can have a different pad capacitance, each sensor input has a control.

CALSENX[1:0]

0 0 1 5-50pF (default) 012 0-25pF 1 0 4 0-12.5pF

R/W CALSEN4[1:0] CALSEN3[1:0] CALSEN2[1:0] CALSEN1[1:0] 00h

R/W CALSEN8[1:0] CALSEN7[1:0] CALSEN6[1:0] CALSEN5[1:0] 00h

Table 5.53 CALSENX Bit Decode

GAIN

CAPACITIVE TOUCH PAD

CAPACITANCE RANGE10

DEFAULT

5.31 Product ID Register

Table 5.54 Product ID Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

FDh R

Product ID

CAP1298-1

The Product ID register stores a unique 8-bit value that identifies the device.

01110001 71h

5.32 Manufacturer ID Register

Table 5.55 Vendor ID Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

FEh RManufacturer ID01011101 5Dh

The Vendor ID register stores an 8-bit value that represents MCHP.

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Datasheet

5.33 Revision Register

Table 5.56 Revision Register

ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT

FFhR Revision 00000000 00h

The Revision register stores an 8-bit value that represen ts the part revision.

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Chapter 6 Package Information

6.1 CAP1298 Package Drawings

Datasheet

Figure 6.1 CAP1298 Package Drawing - 16-Pin QFN 3mm x 3mm

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

Datasheet

Figure 6.2 CAP1298 Package Dim ensions - 16-Pin QFN 3mm x 3mm

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Datasheet

Figure 6.3 CAP1298 PCB Land Pattern and Stencil - 16-Pin QFN 3mm x 3mm

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

BOTTOM

LINE 1: Device code, first 2 of last 6

digits of lot number

LINE 2: Last 4 digits of lot number

TOP

PIN 1

BOTTOM MARKING IS NOT ALLOWED

3 6 L L

L L L L

Datasheet

6.2 Package Marking

Figure 6.4 CAP1298-1 Package Marking

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Appendix A Device Delta

A.1 Delta from CAP1128 / CAP1188 to CAP1298

1. Revision ID set to 00h.

2. Pinout changed. RESET, WAKE, and ADDR_COMM pins removed. LED pins removed. SPI pins /

muxing also removed. Added GND pin as ground slug is no lon ger used for ground connection.

3. Reduced package size from a 20-pin 4mm x 4mm QFN to a 16-pin 3mm x 3mm QFN.

4. Added Power Button feature (see Section 4.6, "Power Button").

5. Added ACAL_FAIL bit to flag analog calibration failures (see Section 5.2, "Status Registers") and

ACAL_FAIL_INT bit to control analog calibration failure interrupts (see Section 5.6, "Configuration

Registers").

6. Added BC_OUT bit to flag calibration failures regarding base counts out of limit (see Se ction 5.2,

"Status Registers") and BC_OUT_RECAL and BC_OUT_INT bit to control base count out of limit

behavior and interrupts (see Section 5.6, "Configuration Registers"). Added Base Count Out of Limit Register to indicate which sensor inputs have base counts outside the operating range (see

Section 5.18, "Base Count Out of Limit Register").

7. New Combo state has been added which allows some sensors programmed to use the Acti ve state

settings and other sensors programmed to use the Standby state settings to function at the same time (see Section 4.3.1.3, "Combo State Sensing Settings").

8. Added an option for a signal guard that is overloaded with the CS5 pin. This signal guard is

configured to power a ground shield for improved sign al in certain applications (see Section 4.5.1,

"Signal Guard").

9. Increased supply voltage range for 5V operation.

Datasheet

10. Increased operating temperature range from 0°C - 85°C to -40°C to 125°C.

11. LEDs removed.

12. SMBus address fixed at 0101_000(r/w).

13. Removed SPI communications protocol option.

14. Removed RESET pin function.

15. Removed WAKE pin function.

16. Removed ALERT

17. Register set changes are shown in Table A.1, "Register Delta".

ADDRESS REGISTER DELTA DELTA DEFAULT

00h

Page 31

02h

Page 33

Added bits - Main

Added bits - General

pin configuration.

Control Register

Status Register

Table A.1 Register Delta

Added C_GAIN[1:0] and COMBO bits.

Changed function of GAIN[1:0] bits if

COMBO bit is set.

Added bit 4 PWR for new Power Button

feature. Added bit 5 ACAL_FAIL to

indicate analog calibration failure. Added

bit 6 BC_OUT. Removed bit 4 LED

status.

00h

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Datasheet

Table A.1 Register Delta (continued)

ADDRESS REGISTER DELTA DELTA DEFAULT

04h

20h

Page 37

26h

Page 44

29h

Page 46

2Eh

Page 50

44h

Page 37

60h

Page 57

61h

Page 58

71h

Removed - LED Status

Removed bit -

Configuration Register

Renamed Calibration

Activate and Status Register and added

functionality

New - Signal Guard

Enable Register

New - Base Count Out

of Limit Register

Added and removed

bits - Configuration 2

New - Power Button

Configuration Register

Removed - LED Output

Type Register

removed register n/a

Removed bit 6 WAKE_CFG. 20h

In addition to forcing a calibration, the

00h

calibration for each sensor input.

new register for Signal Guard feature 00h

new register for calibration status 00h

Added bit 1 ACAL_FAIL_INT. Changed

bit 4 from BLK_POL_MIR to

BC_OUT_INT. Changed bit 6 from

40h

ALT_POL to BC_OUT_RECAL.

Removed bit 7 INV_LINK_TRAN.

new register for Power Button feature 00h

new register for configuring the Power

Button feature

00h

removed register n/a

72h

73h

74h

77h

79h

80h

Page 60

81h

Page 60

82h

84h

Removed - Sensor

Input LED Linking

Removed - LED

Polarity Register

Removed - LED Output

Control Register

Removed - Linked LED

Transition Control

Removed - LED Mirror

Control Register

Added - Calibration Sensitivity Config 1

Changed - Calibration

Sensitivity Config 2

Removed - LED

Behavior Register 2

Removed - LED Pulse

1 Period

removed register n/a

new register for proximity 00h

Changed from LED Behavior register to

new register for proximity

removed register n/a

00h

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Datasheet

Table A.1 Register Delta (continued)

ADDRESS REGISTER DELTA DELTA DEFAULT

85h

86h

88h

90h

91h

92h

93h

94h

95h

FDh

Page 60

Removed - LED Pulse

2 Period

removed register n/a

Removed - LED

Breathe Period

removed register n/a

Removed - LED Config

Removed - LED Pulse

1 Duty Cycle Register

Removed - LED Pulse

2 Duty Cycle Register

removed register n/a

Removed - LED

Breathe Duty Cycle

removed register n/a

Removed - LED Direct

Duty Cycle Register

Removed - LED Direct

Ramp Rates Register

Removed - LED Off

Delay

removed register n/a

Changed - Product ID New product ID for CAP1298-1 71h

FFh

Page 61

Changed - Revision

Revision changed. 00h

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Datasheet

Revision History

Table 6.1 Revision History

REVISION LEVEL AND

DATE SECTION/FIGURE/ENTRY CORRECTION

CAP1298 Revision A replaces the previous SMSC version Re vision 1.0

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8-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard

YSTEM

CERTIFIED BY DNV

== ISO/TS 16949 ==

Datasheet

Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meet s with y our specifications. MICROCHIP MA KES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STA TUT OR Y OR

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The Microchip name and logo, the Microchip logo, dsPIC, FlashFlex, K logo, rfPIC, SST , SST Logo, SuperFlash and UNI/O are registered trademarks of Microchip T echnology Incorporated in the U.S.A. and other countries.

FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MTP, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.

Silicon Storage Technology is a reg istered trademark of Microchip Technology Inc. in other countries. Analog-for-the-Digital Age, Application Maestro, BodyCom, chipKIT, chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net,

dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPF , MPLAB Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, SQI, Serial Quad I/O, Total Endurance, TSHARC, UniWinDriver, WiperLock, ZENA and ZScale are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. GestIC and ULPP are registered trademarks of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip

Technology Inc., in other countries. A more complete list of registered trademarks and common law trademarks owned by Standard Microsystems Corporation (“SMSC”)

is available at: www.smsc.com. The absence of a trademark (name, logo, etc.) from the list does not constitute a waiver of any intellectual property rights that SMSC has established in any of its trademarks.

ISBN: 9781620774496

EELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, PIC

QUALITY MANAGEMENT S

DS01571A-page 70  2013 Microchip Technology Inc.

Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and T empe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the desig n and manufacture of development systems is ISO 9001:2000 certified.

MCUs and dsPIC® DSCs, KEELOQ

code hopping

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08/20/13

DS01571A-page 71  2013 Microchip Technology Inc.

Datasheet CAP1298 Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual

Chapter 1 Pin Description

Figure 1.1 CAP1298-1 Pin Diagram (16-Pin QFN)

Table 1.1 Pin Description for CAP1298

Table 1.2 Pin Types

Chapter 2 Electrical Specifications

Table 2.1 Absolute Maximum Ratings

Table 2.2 Electrical Specifications

Chapter 3 Communications

3.1 Communications

3.2 System Management Bus

Figure 3.1 SMBus Timing Diagram

3.2.1 SMBus Start Bit

3.2.2 SMBus Address and RD / WR Bit

3.2.3 SMBus Data Bytes

3.2.4 SMBus ACK and NACK Bits

3.2.5 SMBus Stop Bit

3.2.6 SMBus Timeout

3.2.7 SMBus and I2C Compatibility

3.3 SMBus Protocols

Table 3.1 Protocol Format

3.3.1 SMBus Write Byte

Table 3.2 Write Byte Protocol

3.3.2 SMBus Read Byte

Table 3.3 Read Byte Protocol

3.3.3 SMBus Send Byte

Table 3.4 Send Byte Protocol

3.3.4 SMBus Receive Byte

Table 3.5 Receive Byte Protocol

3.4 I2C Protocols

3.4.1 Block Read

Table 3.6 Block Read Protocol

3.4.2 Block Write

Table 3.7 Block Write Protocol

Chapter 4 General Description

Figure 4.1 System Diagram for CAP1298

4.1 Power States

4.2 Reset

4.3 Capacitive Touch Sensing

4.3.1 Capacitive Touch Sensing Settings

4.3.2 Sensing Cycle

4.4 Sensor Input Calibration

Table 4.1 Ideal Base Counts

4.4.1 Automatic Recalibration

4.4.2 Negative Delta Count Recalibration

4.4.3 Delayed Recalibration

4.5 Proximity Detection

4.5.1 Signal Guard

4.6 Power Button

Figure 4.3 Signal Guard

4.7 Multiple Touch Pattern Detection

4.8 Noise Controls

4.8.1 Low Frequency Noise Detection

4.8.2 RF Noise Detection

4.8.3 Noise Status and Configuration

4.9 Interrupts

4.9.1 ALERT# Pin

4.9.2 Capacitive Sensor Input Interrupt Behavior

Figure 4.4 Sensor Interrupt Behavior - Repeat Rate Enabled

Figure 4.5 Sensor Interrupt Behavior - No Repeat Rate Enabled

4.9.3 Interrupts for the Power Button

4.9.4 Interrupts for Multiple Touch Pattern Detection

4.9.5 Interrupts for Sensor Input Calibration Failures

4.9.6 Interrupts for Reset

Chapter 5 Register Description

Table 5.1 Register Set in Hexadecimal Order

5.1 Main Control Register

Ta b le 5.2 Main Control Register

T able 5.3 Power State Bit Overrides

Table 5.4 GAIN and C_GAIN Bit Decode

5.2 Status Registers

Table 5.5 Status Registers

5.2.1 General Status - 02h

5.2.2 Sensor Input Status - 03h

5.3 Noise Flag Status Registers

Table 5.6 Noise Flag Status Registers

5.4 Sensor Input Delta Count Registers