Datasheet
8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
Revision 1.32 (01-05-12) 60 SMSC CAP1188
DATASHEET
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
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).
1 0 0 256 256
1 0 1 256 1024
1 1 0 256 2048
1 1 1 256 4096
Table 5.32 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
33h R/W
Sensor Input 4
Threshold
- 64 32 16 8 4 2 1 40h
34h R/W
Sensor Input 5
Threshold
- 64 32 16 8 4 2 1 40h
35h R/W
Sensor Input 6
Threshold
- 64 32 16 8 4 2 1 40h
36h R/W
Sensor Input 7
Threshold
- 64 32 16 8 4 2 1 40h
37h R/W
Sensor Input 8
Threshold
- 64 32 16 8 4 2 1 40h
Table 5.31 CAL_CFG Bit Decode (continued)
CAL_CFG[2:0]
RECALIBRATION
SAMPLES (SEE
Note 5.1)
UPDATE TIME (SEE
Note 5.2)2 1 0