CAP1128 datasheet(43/75 Pages) MICROCHIP

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DS00001622B-page 43

CAP1128

6.15

Multiple Touch Pattern Configuration Register

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:

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.

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. 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.

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

All sensor inputs will remain blocked so long as the requisite number of sensor inputs are above the MTP thresh-

old 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 6-27. This threshold is a percentage of sensor

input threshold (see Section 6.18, "Sensor Input Threshold Registers") when the device is in the Fully Active state or of

the standby threshold (see Section 6.23, "Standby Threshold Register") when the device is in the Standby state.

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 num-

ber will be equal to the number of bits set in the register.

TABLE 6-25:

B_MULT_T BIT DECODE

B_MULT_T[1:0]

Number of Simultaneous Touches

1 (default)

TABLE 6-26:

MULTIPLE TOUCH PATTERN CONFIGURATION

ADDR

R/W

Default

2Bh

R/W

Multiple Touch

Pattern Config

MTP_ EN

MTP_TH[1:0]

COMP_

PTRN

MTP_

ALERT

00h

TABLE 6-27:

MTP_TH BIT DECODE

MTP_TH[1:0]

Threshold Divide Setting

12.5% (default)

25%

37.5%

100%

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