CAP1293 Datasheet, PDF (42/63 Pages) Microchip Technology – 3-Channel Capacitive Touch Sensor with Proximity

CAP1293
5.19 Sensor Input Threshold Registers
TABLE 5-35: SENSOR INPUT THRESHOLD REGISTERS
Addr R/W
Register
B7
B6
B5
B4
B3
B2
B1
B0
Default
30h
R/W
Sensor Input 1
Threshold
-
64
32
16
8
4
2
1
40h
31h
R/W
Sensor Input 2
Threshold
-
64
32
16
8
4
2
1
40h
32h
R/W
Sensor Input 3
Threshold
-
64
32
16
8
4
2
1
40h
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 5.18 - bit 7), writing data to the Sensor Input 1 Threshold register will
update all of the Sensor Input Threshold registers (31h - 32h inclusive).
5.20 Sensor Input Noise Threshold Register
TABLE 5-36: SENSOR INPUT NOISE THRESHOLD REGISTER
Addr
R/W
Register
B7
B6
B5
B4
B3
B2
B1
B0
Default
38h
R/W
Sensor Input
Noise Threshold
-
-
-
-
-
-
CS_BN_TH
[1:0]
01h
The Sensor Input Noise Threshold register controls the value of a secondary internal threshold to detect noise and
improve the automatic recalibration routine. If a capacitive touch sensor input exceeds the Sensor Input Noise Threshold
but does not exceed the sensor input threshold, it is determined to be caused by a noise spike. That sample is not used
by the automatic recalibration routine. This feature can be disabled by setting the DIS_DIG_NOISE bit.
Bits 1-0 - CS1_BN_TH[1:0] - Controls the noise threshold for all capacitive touch sensor inputs, as shown in Table 5-37.
The threshold is proportional to the threshold setting.
TABLE 5-37: CSX_BN_TH BIT DECODE
CS_BN_TH[1:0]
1
0
0
0
0
1
1
0
1
1
Percent Threshold Setting
25%
37.5% (default)
50%
62.5%
DS00001566B-page 42
 2013-2015 Microchip Technology Inc.