LM9627 datasheet(11/37 Pages) NSC

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Functional Description (continued)

2.0

WINDOWING

The integrated timing and control circuit allows any size window

in any position within the active region of the array to be read out

with a 1x1 pixel resolution. The window read out is called the

“Display Window”.

A “Scan Window” must be defined first, by programing the start

and end row addresses as shown in Figure 13. Four coordinates

(start row address, start column address, end row address &

end column address) are programmed to define the size and

location of the “Display Window” to be read out (see Figure 13).

Figure 13. Windowing

Notes:

• The “Display Window” must always be defined within the

“Scan Window”.

• A “Display Window” can only be read out in the progressive

scan mode.

• By default the “Display Window” is the complete array.

2.1

Programming the scan window

Two registers (SROWS & SROWE) are provided to program the

size of the scan window. The start and end row address of the

scan window is given by:

Where:

SwStartRow

is the contents of the Scan Window start row

SwEndROW

is the contents of the Scan Window end row reg-

ister (SROWE)

SwLsb

is bit 6 of the Display Window LSB register

(DWLSB)

2.2

Programming the display window

Five register (DROWS, DROWE, DCOLS, DCOLE and DWLSB)

are provided to program the display window as described in the

3.0

READ OUT MODES

3.1

Progressive Scan Readout Mode

In progressive scan readout mode, every pixel in every row in

the display window is consecutively read out, one pixel at a time,

starting with the left most pixel in the top most row. Hence, for

the example shown in Figure 14, the read out order will be

a0,b0,...,r0 then a1,b1,...,r1 and so on until pixel r20 is read out.

a b c d e f g h i j k l m n o p q r

Column/Horizontal

Figure 14: Progressive Scan Read Out Mode

3.2

Interlaced Readout Mode

In interlaced readout mode, pixels are read out in two fields, an

Odd Field followed by an Even Field.

The Odd Field, consisting of all even row pairs contained within

the display window, is read out first. Each pixel in the “Odd Field”

is consecutively read out, one pixel at a time, starting with the

left most pixel in the top most row pair.

The Even Field, consisting of all odd row pairs contained within

the display window, is then read out. Each pixel in the “Even

Field” is consecutively read out, one pixel at a time, starting with

the left most pixel in the top most row pair.

a b c d e f g h i j k l m n o p q r

Column/Horizontal

Odd Field

Column/Horizontal

Even Field

a b c d e f g h i j k l m n o p q r

Figure 15: Interlace Read Out Mode

Hence, for the example shown in Figure 15, the display window

is broken up into two fields, as shown in Figure 15. Pixels

a0,b0,...,r0 and a1,b1,...,r1 are readout first and so on until pix-

els a17,b17,...r17 in the even field are read out. The even field

read out is followed by pixels in the odd field, a2,b2,...,r2 then

a3,b3,...,r3 until pixels a19,b19,...,r19

display row

Active Pixel Array

Display Window

Scan Window

display row

display col

start address

end address

start address

end address

scan row

start address

scan row

end address

scan row start address = (2* SwStartRow) + SwLsb

scan row end address = (2* SwEndRow) + 1 + SwLsb

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