AD9891 datasheet(20/58 Pages) AD

20 / 58 page

REV. A

–20–

AD9891/AD9895

Complete Field: Combining the Regions

The individual regions are combined into a complete field readout

by using region change positions (RCP) and region pointers

(REGPTR). Figure 22 shows how each field is divided into

multiple regions. This allows the user to change the vertical

timing during various stages of the image readout. The boundaries

of each region are defined by the sequence change positions

(RCP). Each RCP is a 12-bit value representing the line number

bounding the region. A total of seven RCPs allow up to eight

different region areas in the field to be defined. The first RCP is

always hard-coded to zero, and the remaining seven are register

programmable. Note that there are only five possible individual

regions that can be defined, but the eight region areas allow the

same region to be used in more than one place during the field.

Within each region area, the region pointers specify which of the

five individual regions will be used. There are eight region

pointers, one for each region area. Table IX summarizes the

registers for the region change positions and region pointers.

UP TO EIGHT V-CLOCK REGION AREAS MAY BE DEFINED WITHIN ONE FIELD BY

USING THE REGION CHANGE POSITION AND THE REGION POINTERS.

REGION CHANGE POSTION #1

REGION CHANGE POSTION #2

REGION CHANGE POSTION #3

REGION CHANGE POSTION #4

REGION CHANGE POSTION #5

SINGLE FIELD (1 VD INTERVAL)

USE THE REGION SPECIFIED BY REGION POINTER 0

REGION CHANGE POSTION #0

(V-COUNTER = 0)

REGION CHANGE POSTION #6

REGION CHANGE POSTION #7

USE THE REGION SPECIFIED BY REGION POINTER 6

USE THE REGION SPECIFIED BY REGION POINTER 5

USE THE REGION SPECIFIED BY REGION POINTER 4

USE THE REGION SPECIFIED BY REGION POINTER 3

USE THE REGION SPECIFIED BY REGION POINTER 2

USE THE REGION SPECIFIED BY REGION POINTER 1

USE THE REGION SPECIFIED BY REGION POINTER 7

Figure 22. Complete Field Using Multiple Region Areas

Table VIII. Individual Vertical Region Parameters

Length

Range

Description

HDLEN

12b

0–4095 Pixels

HD Line Length for Lines in Each Region 0–4

VxSTART

12b

0–4095 Pixel Location

Sequence Start Position for Each Vx Output in Each Region 0–4

VxSPTRFIRST

Sequence 0–11

Sequence Pointer for Vx Output during Each Region 0–4

(Can Be Used with SPTRSECOND for Alternation, See Text)

VxINVFIRST

High/Low

When High, the Polarity of Sequence VxSPTRFIRST Is Inverted

x is the V-output from 1–4.

Table IX. Complete Vertical Field Registers

Length

Range

Description

VTPRCP

12b

0–4095 Line Location

Region Change Position for each Region Area in Field

VTPREGPTR

Region 0–4Region Pointer for each Region Area of Field

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