8 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
Table 5.31 CAL_CFG Bit Decode (continued)
CAL_CFG[2:0]
1
RECALIBRATION
SAMPLES (SEE
Note 5.1)
UPDATE TIME (SEE
2
0
Note 5.2)
0
1
1
1
1
1
0
0
1
1
1
0
1
0
1
128
256
256
256
256
128
256
1024
2048
4096
Note 5.1 Recalibration Samples refers to the number of samples that are measured and averaged
before the Base Count is updated however does not control the base count update period.
Note 5.2 Update Time refers to the amount of time (in polling cycle periods) that elapses before the
Base Count is updated. The time will depend upon the number of channels active, the
averaging setting, and the programmed cycle time.
5.18
Sensor Input Threshold Registers
Table 5.32 Sensor Input Threshold Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
Sensor Input 1
Threshold
30h
R/W
-
64
32
16
8
4
2
1
40h
Sensor Input 2
Threshold
31h
32h
33h
34h
35h
36h
37h
R/W
R/W
R/W
R/W
R/W
R/W
R/W
-
-
-
-
-
-
-
64
64
64
64
64
64
64
32
32
32
32
32
32
32
16
16
16
16
16
16
16
8
8
8
8
8
8
8
4
4
4
4
4
4
4
2
2
2
2
2
2
2
1
1
1
1
1
1
1
40h
40h
40h
40h
40h
40h
40h
Sensor Input 3
Threshold
Sensor Input 4
Threshold
Sensor Input 5
Threshold
Sensor Input 6
Threshold
Sensor Input 7
Threshold
Sensor Input 8
Threshold
The Sensor Input Threshold registers store the delta threshold that is used to determine if a touch has
been detected. When a touch occurs, the input signal of the corresponding sensor pad changes due
to the capacitance associated with a touch. If the sensor input change exceeds the threshold settings,
a touch is detected.
When the BUT_LD_TH bit is set (see Section 5.17 - bit 7), writing data to the Sensor Input 1 Threshold
register will update all of the sensor input threshold registers (31h - 37h inclusive).
SMSC CAP1128
Revision 1.32 (01-05-12)
DATA5S9HEET
SMSC [ SMSC CORPORATION ]
