8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
The Standby Threshold registers stores 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.
5.22 Sensor Base Count Registers
Table 5.36 Sensor Base Count Registers
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
Sensor 1 Base
Count
50h
R
128
64
32
16
8
4
2
1
C8h
Sensor 2 Base
Count
51h
52h
53h
54h
55h
56h
57h
R
R
R
R
R
R
R
128
128
128
128
128
128
128
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
C8h
C8h
C8h
C8h
C8h
C8h
C8h
Sensor 3 Base
Count
Sensor 4 Base
Count
Sensor 5 Base
Count
Sensor 6 Base
Count
Sensor 7 Base
Count
Sensor 8 Base
Count
The Sensor Base Count registers store the calibrated “Not Touched” input value from the Capacitive
Touch Sensor inputs. These registers are periodically updated by the re-calibration routine.
The routine uses an internal adder to add the current count value for each reading to the sum of the
previous readings until sample size has been reached. At this point, the upper 16 bits are taken and
used as the Sensor Base Count. The internal adder is then reset and the re-calibration routine
continues.
The data presented is determined by the BASE_SHIFT[3:0] bits (see Section 5.5).
5.23 LED Output Type Register
Table 5.37 LED Output Type Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
LED Output
Type
LED8_
OT
LED7_
OT
LED6_
OT
LED5_
OT
LED4_
OT
LED3_
OT
LED2_
OT
LED1_
OT
71h
R/W
00h
The LED Output Type register controls the type of output for the LED pins. Each pin is controlled by
a single bit.
SMSC CAP1088
Revision 1.1 (08-05-09)
DATA5S3HEET
SMSC [ SMSC CORPORATION ]
