Datasheet

8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
SMSC CAP1188 69 Revision 1.32 (01-05-12)
DATASHEET
5.29 Linked LED Transition Control Register
The Linked LED Transition Control register controls the LED drive when the LED is linked to a
capacitive touch sensor input. These controls work in conjunction with the INV_LINK_TRAN bit (see
Section 5.6.2, "Configuration 2 - 44h") to create smooth transitions from host control to linked LEDs.
Bit 7 - LED8_LTRAN - Determines the transition effect when LED8 is linked to CS8.
‘0’ (default) - When the LED output control bit for CS8 is ‘1’, and then CS8 is linked to LED8 and
no touch is detected, the LED will change states.
‘1’ - If the INV_LINK_TRAN bit is ‘1’, when the LED output control bit for CS8 is ‘1’, and then CS8
is linked to LED8 and no touch is detected, the LED will not change states. In addition, the LED
state will change when the sensor pad is touched. If the INV_LINK_TRAN bit is ‘0’, when the LED
output control bit for CS8 is ‘1’, and then CS8 is linked to LED8 and no touch is detected, the LED
will not change states. However, the LED state will not change when the sensor pad is touched.
Table 5.48 LED Polarity Behavior
LED
OUTPUT
CONTROL
REGISTER
OR TOUCH POLARITY MAX DUTY MIN DUTY BRIGHTNESS
LED
APPEARANCE
0
inverted
(‘0’)
not used
minimum % of
time that the LED
is on (logic 0)
maximum brightness
at min duty cycle
on at min duty
cycle
1
inverted
(‘0’)
maximum % of
time that the LED
is on (logic 0)
minimum % of
time that the LED
is on (logic 0)
maximum brightness
at max duty cycle.
Brightness ramps
from min duty cycle
to max duty cycle
according to
LED behavior
0
non-
inverted
(‘1’)
not used
minimum % of
time that the LED
is off (logic 1)
maximum brightness
at 100 minus min
duty cycle.
on at 100 - min
duty cycle
1
non-
inverted
(‘1’)
maximum % of
time that the LED
is off (logic 1)
minimum % of
time that the LED
is off (logic 1)
For Direct behavior,
maximum brightness
is 100 minus max
duty cycle. When
breathing, max
brightness is 100
minus min duty cycle.
Brightness ramps
from 100 - min duty
cycle to 100 - max
duty cycle.
according to
LED behavior
Table 5.49 Linked LED Transition Control Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
77h R/W
Linked LED
Transition
Control
LED8_
LTRAN
LED7_
LTRAN
LED6_
LTRAN
LED5_
LTRAN
LED4_
LTRAN
LED3_
LTRAN
LED2_
LTRAN
LED1_
LTRAN
00h