CAP1026 datasheet(54/70 Pages) SMSC

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6 Channel Capacitive Touch Sensor with 2 LED Drivers

Datasheet

Revision 1.1 (08-05-09)

SMSC CAP1026

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

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.

Table 5.40 LED Output Control Register

ADDR

R/W

DEFAULT

74h

R/W

LED Output

Control

---

LED2_

LED1_

00h

CAP1026 Datasheet(PDF) 54 Page - SMSC Corporation

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