TVP3025 datasheet(49/99 Pages) TI

49 / 99 page

2–35

In this way, the video timing relationship is maintained since the same method and pipeline delay are applied

to the SYSBL and VGABL signals.

Figure 2–14 demonstrates the use of OVS to produce a custom overscan screen border.

OVS

Blank

Overscan Border

Display Area

Figure 2–14. Overscan

2.3.12

Horizontal Zooming

The TVP3025 supports a user-programmable horizontal zooming function of 2, 4, 8, 16, or 32x. Zooming

can be controlled through the auxiliary control register on the indirect register map as shown by the following

table. The RCLK divide ratio also has to be modified in the output-clock-selection register.

ACR7

ACR6

ACR5

HORIZONTAL ZOOM

1x (default)

16x

32x

When one of the horizontal zooms (besides 1x) is chosen, the internal pixel multiplexer is configured such

that it replicates the pixel data on successive dot clocks by the number of times specified by ACR(5 –7). Also

the RCLK divide ratio must be modified in the output-clock-selection register to facilitate the pixel replication.

The new RCLK divide ratio should be chosen as the old RCLK divide ratio multiplied by the zoom factor.

It is recommended that the zoom only be changed during vertical retrace.

The horizontal zoom function applies only to the pixel port (P0 – 63) data. VGA data is not zoomed.

TVP3025 Datasheet(PDF) 49 Page - Texas Instruments