CAP1128 datasheet(52/75 Pages) MICROCHIP

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CAP1128

DS00001622B-page 52

 2015 Microchip Technology Inc.

Table 6-48 shows the interaction between the polarity controls, output controls, and relative brightness.

Bit 1 - LED2_DR - Determines whether LED2 output is driven high or low.

• ‘0’ (default) - The LED2 output is driven at the minimum duty cycle or not actuated.

• ‘1’ - The LED2 output is High Z or driven at the maximum duty cycle or actuated.

Bit 0 - LED1_DR - Determines whether LED1 output is driven high or low.

6.29

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 6.6.2, "Configuration 2 - 44h") to

create smooth transitions from host control to linked LEDs.

Bit 1 - LED2_LTRAN - Determines the transition effect when LED2 is linked to CS2.

• ‘0’ (default) - When the LED output control bit for LED2 is ‘1’, and then LED2 is linked to CS2 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 CS2 is ‘1’, and then CS2 is linked to LED2

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 CS2 is ‘1’, and then CS2 is

linked to LED2 and no touch is detected, the LED will not change states. However, the LED state will not change

when the sensor pad is touched.

APPLICATION NOTE: If the LED behavior is not “Direct” and the INV_LINK_TRAN bit it ‘0’, the LED will not perform

as expected when the LED2_LTRAN bit is set to ‘1’. Therefore, if breathe and pulse

behaviors are used, set the INV_LINK_TRAN bit to ‘1’.

TABLE 6-48:

LED POLARITY BEHAVIOR

LED Output

Control

Touch

Polarity

Max Duty

Min Duty

Brightness

LED Appearance

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

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. Bright-

ness ramps from min

duty cycle to max duty

cycle

according to LED

behavior

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

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 breath-

ing, 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 6-49:

LINKED LED TRANSITION CONTROL REGISTER

ADDR

R/W

Default

77h

R/W

Linked LED Tran-

sition Control

LED2_

LTRAN

LED1_

LTRAN

00h

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