WM8224 datasheet(28/50 Pages) WOLFSON

28 / 50 page

WM8224

Production Data

PD, Rev 4.1, June 2012

METHOD 2: REGISTER WRITE

The start of a line can also be indicated using a register write to TG_REG. The first rising edge of

MCLK after TG_REG goes high will indicate the start of the line. TG_REG shall be automatically set

to zero by the device. This process can be repeated to indicate the start of a second line, as shown

in Figure 25. Set TG_METHOD to ‘00’

Figure 25 Start of Line Indicator Using TG_REG

BLC DURATION CONTROL

DUMMY PIXEL DELAY

Once the start of line has been determined there can be a delay to allow for the dummy pixels at the

start of the sensor to be ignored. This is controlled by BLC_DEL, which is the number of pixels there

should be between the start of line indicator and the start of the BLC routine.

The register BPIX_AVAIL must also be set up for the number of black pixels available to carry out the

calibration. The durations of the Coarse Adjust Calibration and Fine Adjust calibration can then be

determined as detailed below.

Figure 26 BLC Duration Control

COARSE ADJUST CALIBRATION ITERATION DURATION

The duration of one iteration of the Coarse Adjust is an integer number of VSMP periods. The exact

number of VSMP periods depends on the MCLK:VSMP ratio and the number of channels used. The

implementation ensures that there are at least a certain number of MCLK’s per Coarse Adjust

iteration as shown in Table 4.

WM8224 Datasheet(PDF) 28 Page - Wolfson Microelectronics plc