Multiple Channel Capacitive Touch Sensor and LED Driver
Datasheet
Table 5.40 Sensor Threshold Registers (continued)
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
Sensor 3
Threshold
32h
R/W
-
64
32
16
8
4
2
1
40h
Sensor 4
Threshold
33h
34h
35h
36h
37h
R/W
R/W
R/W
R/W
R/W
-
-
-
-
-
64
64
64
64
64
32
32
32
32
32
16
16
16
16
16
8
8
8
8
8
4
4
4
4
4
2
2
2
2
2
1
1
1
1
1
40h
40h
40h
40h
40h
Sensor 5
Threshold
Sensor 6
Threshold
Sensor 7
Threshold
Group
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 5.27 - bit 7), writing data to the Sensor 1 Threshold
register will update all of the button threshold registers (31h - 36h inclusive).
When the GP_LD_TH bit is set (see Section 5.27 - bit 6), writing data to the Sensor 1 Threshold
register (30h) will update the Group Threshold register (37h). Individual button registers may be
updated independently of the Sensor 1 Threshold settings.
5.29 Button Noise Threshold Registers
Table 5.41 Button Noise Threshold Registers
B7 B6 B5 B4 B3
ADDR
R/W
REGISTER
B2
B1
B0
DEFAULT
Button Noise
Threshold 1
CS4_BN_TH
[1:0]
CS3_BN_TH
[1:0]
CS2_BN_TH
[1:0]
CS1_BN_TH
[1:0]
38h
R/W
55h
Button Noise
Threshold 2
GR_BN_TH
[1:0]
CS7_BN_TH
[1:0]
CS6_BN_TH
[1:0]
CS5_BN_TH
[1:0]
39h
R/W
55h
The Button Noise Threshold registers control the value of a secondary internal threshold to detect
noise and improve the automatic recalibration routine. If a Capacitive Touch Sensor output exceeds
the Button Noise Threshold but does not exceed the sensor threshold, then it is determined to be
caused by a noise spike. That sample is not used by the automatic re-calibration routine.
The Button Noise Threshold is proportional to the programmed threshold as shown in Table 5.42.
Revision 1.65 (08-11-09)
SMSC CAP1014
DATA5S6HEET
SMSC [ SMSC CORPORATION ]
