CAP1126 datasheet(53/73 Pages) MICROCHIP

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 2015 Microchip Technology Inc.

DS00001623B-page 53

CAP1126

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.

6.32

LED Pulse 1 Period Register

The LED Pulse Period 1 register determines the overall period of a pulse operation as determined by the LED_CTL

registers (see Table 6-52 - setting 01b). The LSB represents 32ms so that a setting of 18h (24d) would represent a

period of 768ms (24 x 32ms = 768ms). The total range is from 32ms to 4.064 seconds as shown in Table 6-54 with the

default being 1024ms.

APPLICATION NOTE: Due to constraints on the LED Drive PWM operation, any Breathe Period less than 160ms

(05h) may not be achievable. The device will breathe at the minimum period possible as

determined by the period and min / max duty cycle settings.

Bit 7 - ST_TRIG - Determines the start trigger for the LED Pulse behavior.

• ‘0’ (default) - The LED will Pulse when a touch is detected or the drive bit is set.

• ‘1’ - The LED will Pulse when a release is detected or the drive bit is cleared.

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

TABLE 6-53:

LED PULSE 1 PERIOD REGISTER

ADDR

R/W

Default

84h

R/W

LED Pulse 1

Period

ST_

TRIG

P1_

PER6

P1_

PER5

P1_

PER4

P1_

PER3

P1_

PER2

P1_

PER1

P1_

PER0

20h

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