CAP1126 datasheet(42/73 Pages) MICROCHIP

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CAP1126

DS00001623B-page 42

 2015 Microchip Technology Inc.

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.

• ‘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.

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.

6.16

Multiple Touch Pattern Register

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 6.15). The methods are described below.

Specific Sensor Inputs: If, during a single polling 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.

Number of Sensor Inputs: If, during a single polling 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.

TABLE 6-27:

MTP_TH BIT DECODE

MTP_TH[1:0]

Threshold Divide Setting

12.5% (default)

25%

37.5%

100%

TABLE 6-28:

MULTIPLE TOUCH PATTERN REGISTER

ADDR

R/W

Default

2Dh

R/W

Multiple

Touch Pattern

CS6_

PTRN

CS5_

PTRN

CS4_

PTRN

CS3_

PTRN

CS2_

PTRN

CS1_

PTRN

3Fh

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