WM8255 datasheet(44/49 Pages) CIRRUS

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Production Data

WM8255

PD, Rev 4.7, August 2013

BIT

BIT NAME(S)

DEFAULT

DESCRIPTION

Setup

6:0

LEDSTOPR [6:0]

0010000

Sets the LED stop time for the RED LED.

LEDSTART [4]

Sets the next significant bit of the 7 bit LEDSTART time. [4]

PGA gain

(Red)

7:0

PGAR[7:0]

Determines the gain of the red channel PGA according to the equation:

Red channel PGA gain = [0.78+(PGAR[7:0]*7.57)/255]. Used under

control of the INTM[1:0] control bits.

PGA gain

(Green)

7:0

PGAG[7:0]

Determines the gain of the green channel PGA according to the

equation:

Green channel PGA gain = [0.78+(PGAG[7:0]*7.57)/255]. Used under

control of the INTM[1:0] control bits.

PGA gain

(Blue)

7:0

PGAB[7:0]

Determines the gain of the blue channel PGA according to the equation:

Blue channel PGA gain = [0.78+(PGAB[7:0]*7.57)/255]. Used under

control of the INTM[1:0] control bits.

PGA gain

(RGB)

7:0

PGA[7:0]

A write to this register location causes the red, green and blue PGA gain

registers to be overwritten by the new value

Setup

6:0

LEDSTOPG [6:0]

0010000

Sets the LED stop time for the GREEN LED.

LEDSTART [5]

Sets the next significant bit of the 7 bit LEDSTART time. [5]

Setup

6:0

LEDSTOPB [6:0]

0010000

Sets the LED stop time for the BLUE LED.

LEDSTART [6]

Sets the MSB of the 7 bit LEDSTART time. [6]

Setup

5:0

INITBLANK [8:3]

000000

Sets the 6 MSBs of the 9 bit register to adjust the initial blank period

following a sequence transition. The 3 LSBs are fixed to zero. Must be

set so the initial blank period is 25

s. See Initial Blank Period on page

25 for details.

ILIMITDEC

When ILIMITEN = 0 this register has no effect.

When the maximum LED current limit is exceeded and the ILIMITFLAG

is set, the current is reduced to a safe level to protect the LED.

0 = 12.5% reduction in current

1 = 25% reduction in current

ILIMITFLAG

When ILIMITEN=00 this read register will not be active.

Read only register. Set high by the device when the current limit has

been exceeded.

LED

Reset

Resets all LED timing control to its reset state at register write

LED RGB

FLAGS

LEDBFLAG

Set high by the device when the current limit has been exceeded for the

Blue LED. May be read.

LEDGFLAG

Set high by the device when the current limit has been exceeded for the

Green LED. May be read.

LEDRFLAG

Set high by the device when the current limit has been exceeded for the

Red LED. May be read.

Table 10 Register Control Bits

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