8 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
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.
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 5.27. This threshold is a
percentage of sensor input threshold (see Section 5.18, "Sensor Input Threshold Registers") when the
device is in the Fully Active state or of the standby threshold (see Section 5.23, "Standby Threshold
Register") when the device is in the Standby state.
Table 5.27 MTP_TH Bit Decode
MTP_TH[1:0]
1
0
THRESHOLD DIVIDE SETTING
0
0
1
1
0
1
0
1
12.5% (default)
25%
37.5%
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.
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.
Revision 1.32 (01-05-12)
SMSC CAP1128
DATA5S6HEET
SMSC [ SMSC CORPORATION ]
