CAP1208 Datasheet, PDF (46/67 Pages) Microchip Technology – 8-Channel Capacitive Touch Sensor

8-Channel Capacitive Touch Sensor
Datasheet
5.16
Table 5.26 MTP_TH Bit Decode
MTP_TH[1:0]
1
0
THRESHOLD DIVIDE SETTING
0
0
12.5% (default)
0
1
25%
1
0
37.5%
1
1
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.
 ‘1’ - If an MTP event occurs, the ALERT# pin will be asserted.
Multiple Touch Pattern Register
Table 5.27 Multiple Touch Pattern Register
ADDR R/W
2Dh R/W
REGISTER B7
B6
Multiple
Touch
Pattern
CS8_ CS7_
PTRN PTRN
B5
CS6_
PTRN
B4
CS5_
PTRN
B3
CS4_
PTRN
B2
CS3_
PTRN
B1
CS2_
PTRN
B0 DEFAULT
CS1_
PTRN
FFh
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 5.15). The methods are described below.
1. Specific Sensor Inputs: If, during a single sensing 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.
2. Number of Sensor Inputs: If, during a single sensing 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.
DS00001570B-page 46
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