CAP1126 datasheet(51/73 Pages) MICROCHIP

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DS00001623B-page 51

CAP1126

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’.

Bit 0 - LED1_LTRAN - Determines the transition effect when LED1 is linked to CS1.

6.30

LED Mirror Control Register

The LED Mirror Control Registers determine the meaning of duty cycle settings when polarity is non-inverted for each

LED channel. When the polarity bit is set to ‘1’ (non-inverted), to obtain correct steps for LED ramping, pulse, and

breathe behaviors, the min and max duty cycles need to be relative to 100%, rather than the default, which is relative

to 0%.

APPLICATION NOTE: The LED drive assumes that the LEDs are configured such that if the LED pin is driven to

a logic ‘0’, the LED will be on and the CAP1126 LED pin is sinking the LED current. When

the polarity bit is set to ‘1’, it is considered non-inverted. For systems using the opposite LED

configuration, mirror controls would apply when the polarity bit is ‘0’.

These bits are changed automatically if the corresponding LED Polarity bit is changed (unless the BLK_POL_MIR bit is

set - see Section 6.6).

Bit 1 - LED2_MIR_EN - Determines whether the duty cycle settings are “biased” relative to 0% or 100% duty cycle.

• ‘0’ (default) - The duty cycle settings are determined relative to 0% and are determined directly with the settings.

• ‘1’ - The duty cycle settings are determined relative to 100%.

Bit 0 - LED1_MIR_EN - Determines whether the duty cycle settings are “biased” relative to 0% or 100% duty cycle.

6.31

LED Behavior Register

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

TABLE 6-50:

LED MIRROR CONTROL REGISTER

ADDR

R/W

Default

79h

R/W

LED Mirror Con-

trol

LED2_

MIR _

LED1_

MIR _

00h

TABLE 6-51:

LED BEHAVIOR REGISTER

ADDR

R/W

Default

81h

R/W

LED Behavior 1

LED2_CTL[1:0]

LED1_CTL[1:0]

00h

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