6 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
Finally, the breathe operations will always ramp the duty cycle from the minimum duty cycle
to the maximum duty cycle and then back down to the minimum duty cycle.
The LED Polarity controls lead to two conditions that have the apparent effect of changing
the duty cycle settings. If an LED output is non-inverted then the Maximum Duty Cycle
settings will define the maximum % of time that the LED is off. Conversely the Minimum
Duty Cycle settings will define the minimum % of time that the LED is off. As well, when
there is no touch detected or the LED Output Control register bit is at a logic ‘0’ then the
LED output will be driven at the minimum duty cycle setting. The relative brightness will then
ramp from maximum to minimum and back.
If an LED output is inverted, then the Maximum Duty Cycle settings will define the maximum
% of time that the LED is on and the Minimum Duty Cycle settings will determine the
minimum % of time that the LED is on. As well, when there is no touch detected, or the LED
Output Control register bit is at a logic ‘0’, then the LED output will be driven at the minimum
duty cycle setting. The relative brightness will then ramp from minimum to maximum and
back.
Bit 1 - LED2_POL - Determines the polarity of the LED2 output.
‘0’ - The LED2 output is inverted. A setting of ‘1’ in the LED Output register will cause the output
to be driven to a logic ‘0’ as determined by the LED behavior. Similarly, the duty cycles
corresponding to Pulse and Breathe operations will indicate the amount of time that the LED is
driven to a logic ‘0’ state (corresponding to “active”).
‘1’ - The LED2 output is non-inverted. A setting of ‘1’ in the LED Output register will cause the
output to be driven to a logic ‘1’ or left in the high-z state as determined by its output type and LED
behavior. Similarly, the duty cycles corresponding to Pulse and Breathe operations will indicate to
the amount of time that the LED is driven to a logic ‘1’ state (corresponding to “inactive”).
Bit 0 - LED1_POL - Determines the polarity of the LED1 output.
5.26 LED Output Control Register
Table 5.40 LED Output Control Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
LED Output
Control
LED2_
DR
LED1_
DR
74h
R/W
-
-
-
-
-
-
00h
The LED Output Control Register controls the output state of the LED pins.
All LEDs that are associated with a Capacitive Touch Sensor channel are automatically enabled and
will be actuated per the LED Behavior.
For those LEDs that are not linked with a Capacitive Touch Sensor channel, then the bit state
determines whether the LED is actuated or not actuated.
The LED Polarity Control register will determine the non actuated state of the LED pins.
Table 5.41 shows the interaction between the polarity controls, output controls and relative brightness.
Revision 1.1 (08-05-09)
SMSC CAP1026
DATA5S4HEET
SMSC [ SMSC CORPORATION ]
