
On-Screen Display Module (OSD)
Display Characteristics
MC68HC908TV24 — Rev. 2.1
Advance Information
Freescale Semiconductor
On-Screen Display Module (OSD)
229
The background is the region of the character matrix where ROM pixels
are zero and there are no rounding, black outline or underline dots.
Background may be a solid color or transparent, in which case the video
will show through (regardless of border color selection).
Border is displayed wherever there is no foreground or background
inside the active display area. Border may also be a solid color or
transparent. Border can be specified for a character within a row by
using the border space character. When background or border are
transparent, the video intensity can be specified to be half-tone to
improve readability.
The horizontal delay of the active display area from each HSYNC pulse
is given by a minimum fixed delay of 14.1
s plus an additional delay
specified on the horizontal delay register (32 increments of 0.14
s). This
delay does not depend on the character size programmed for each row.
The border space character can be used to provide further indentation
in a row-by-row basis.
Vertical positioning of the active display area is specified in the vertical
delay register. This delay is measured in lines from the starting edge of
the vertical sync pulse. Vertical positioning inside the active display area
is indicated by the contents of the event line register.
Scrolling can be accomplished in software by modifying the vertical
positioning of a row, in conjunction with specifying the subset of
horizontal lines of the row to display. The matrix start register and the
matrix end register indicate, respectively, the first and last lines of a row
to be displayed. All lines before and after the lines displayed are filled in
with border.
Boundaries between border and character display are always vertical. If
italics are not enabled, the width of a border space character is the same
as the width of a ROM character. If italics are enabled, the boundaries of
the border space character are not slanted, but the width occupied by
this space is smaller than the width of a ROM character by five dots (see