CAP1128 datasheet(54/75 Pages) MICROCHIP

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CAP1128

DS00001622B-page 54

 2015 Microchip Technology Inc.

APPLICATION NOTE: If an LED is actuated and not linked and the desired LED behavior is changed, this new

behavior will take effect immediately; however, the first instance of the changed behavior

may act incorrectly (e.g. if changed from Direct to Pulse 1, the LED output may ‘breathe’ 4

times and then end at minimum duty cycle). LED Behaviors will operate normally once the

LED has been un-actuated and then re-actuated.

APPLICATION NOTE: If an LED is actuated and it is switched from linked to a capacitive touch sensor input to

unlinked (or vice versa), the LED will respond to the new command source immediately if

the behavior was Direct or Breathe. For Pulse behaviors, it will complete the behavior

already in progress. For example, if a linked LED was actuated by a touch and the control

is changed so that it is unlinked, it will check the status of the corresponding LED Output

Control bit. If that bit is ‘0’, then the LED will behave as if a release was detected. Likewise,

if an unlinked LED was actuated by the LED Output Control register and the control is

changed so that it is linked and no touch is detected, then the LED will behave as if a release

was detected.

Bits 3 - 2 - LED2_CTL[1:0] - Determines the behavior of LED2 as shown in Table 6-52.

Bits 1 - 0 - LED1_CTL[1:0] - Determines the behavior of LED1 as shown in Table 6-52.

APPLICATION NOTE: The PWM frequency is determined based on the selected LED behavior, the programmed

breathe period, and the programmed min and max duty cycles. For the Direct behavior

mode, the PWM frequency is calculated based on the programmed Rise and Fall times. If

these are set at 0, then the maximum PWM frequency will be used based on the

programmed duty cycle settings.

TABLE 6-52:

LEDX_CTL BIT DECODE

LEDx_CTL

[1:0]

Operation

Description

Start TRigger

Stop Trigger

Direct

The LED is driven to the programmed state

(active or inactive). See Figure 6-7

Touch Detected or

LED Output Con-

trol bit set

Release

Detected or

LED Output

Control bit

cleared

Pulse 1

The LED will “Pulse” a programmed number

of times. During each “Pulse” the LED will

breathe up to the maximum brightness and

back down to the minimum brightness so that

the total “Pulse” period matches the pro-

grammed value.

Touch or Release

Detected or LED

Output Control bit

set or cleared

(see Section 6.32)

n/a

Pulse 2

The LED will “Pulse” when the start trigger is

detected. When the stop trigger is detected, it

will “Pulse” a programmable number of times

then return to its minimum brightness.

Touch Detected or

LED Output Con-

trol bit set

Release

Detected or

LED Output

Control bit

cleared

Breathe

The LED will breathe. It will be driven with a

duty cycle that ramps up from the pro-

grammed minimum duty cycle (default 0%) to

the programmed maximum duty cycle duty

cycle (default 100%) and then back down.

Each ramp takes up 50% of the programmed

period. The total period of each “breath” is

determined by the LED Breathe Period con-

trols - see Section 6.34.

Touch Detected or

LED Output Con-

trol bit set

Release

Detected or

LED Output

Control bit

cleared

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