CAP1298 datasheet(29/68 Pages) MICROCHIP

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DS00001571B-page 29

CAP1298

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 5.15, "Multiple Touch Pattern Configuration Reg-

ister"). 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

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 detected. 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 respective capacitive 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

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 detector or the RF noise detector (see Section 4.8.3, "Noise Status and Configura-

tion"). 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.

TABLE 5-6:

NOISE FLAG STATUS REGISTERS

Addr

R/W

B5B4

B2B1

Default

0Ah

Noise Flag

Status

CS8_

NOISE

CS7_

NOISE

CS6_

NOISE

CS5_

NOISE

CS4_

NOISE

CS3_

NOISE

CS2_

NOISE

CS1_

NOISE

00h

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