CAP1106 datasheet(22/48 Pages) MICROCHIP

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CAP1106

DS00001624B-page 22

 2015 Microchip Technology Inc.

6.3

Noise Flag Status Registers

The Noise Flag Status registers store status bits that are generated from the analog block if the detected noise is above

the operating region of the analog detector or the RF noise detector. 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 5.2.4, "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.

6.4

Sensor Input Delta Count Registers

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 5.2.1, "Sensing Cycle").

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 6.5).

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

6.5

Sensitivity Control Register

TABLE 6-5:

NOISE FLAG STATUS REGISTERS

ADDR

R/W

Default

0Ah

Noise Flag Status

CS6_

NOISE

CS5_

NOISE

CS4_

NOISE

CS3_

NOISE

CS2_

NOISE

CS1_

NOISE

00h

TABLE 6-6:

SENSOR INPUT DELTA COUNT REGISTERS

ADDR

R/W

B5B4

B3B2

B1B0

Default

10h

Sensor Input 1

Delta Count

Sign

00h

11h

Sensor Input 2

Delta Count

Sign

00h

12h

Sensor Input 3

Delta Count

Sign

00h

13h

Sensor Input 4

Delta Count

Sign

00h

14h

Sensor Input 5

Delta Count

Sign

00h

15h

Sensor Input 6

Delta Count

Sign

00h

TABLE 6-7:

SENSITIVITY CONTROL REGISTER

ADDR

R/W

Default

1Fh

R/W

Sensitivity Control

DELTA_SENSE[2:0]

BASE_SHIFT[3:0]

2Fh

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