8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
Table 5.25 CAL_CFG Bit Decode (continued)
CAL_CFG[2:0]
1
RECALIBRATION
SAMPLES (SEE
Note 5.1)
UPDATE TIME (SEE
2
0
Note 5.2)
1
1
1
0
1
1
1
0
1
256
256
256
2048
4096
7936
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.
Once this target number of update cycles is reached, the device may wait additional time
as determined by the Update Time before the base count is updated as determiend by the
settings.
Note 5.2 Update Time refers to the amount of time (in polling cycle periods) that elapses before the
Base Count is updated. For those settings that have the Update Time greater than the
Recalibration Samples value, the device will wait (and continue to average the updated
base count) until the Update Time has elapsed before the base count is updated.
5.16 Sensor Threshold Registers
Table 5.26 Sensor Threshold Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
Sensor 1
Threshold
30h
R/W
-
64
32
16
8
4
2
1
40h
Sensor 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 3
Threshold
Sensor 4
Threshold
Sensor 5
Threshold
Sensor 6
Threshold
Sensor 7
Threshold
Sensor 8
Threshold
The Sensor 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 changes due to the
capacitance associated with a touch. If the sensor input change exceeds the threshold settings, then
a touch is detected.
When the BUT_LD_TH bit is set (see Section 5.15 - bit 7), writing data to the Sensor 1 Threshold
register will update all of the sensor threshold registers (31h - 37h inclusive).
Revision 1.1 (08-05-09)
SMSC CAP1088
DATA4S8HEET
SMSC [ SMSC CORPORATION ]
