ST92196A STMicroelectronics, ST92196A Datasheet - Page 114

• Manufacturer Part Number: ST92196A
• Description: 8/16-bit Mcu For Tv Applications With Up To 96k Rom, On-screen-display And 1 Or 2 Data Slicers
• Manufacturer: STMicroelectronics

8.5 ON SCREEN DISPLAY CONTROLLER (OSD)
8.5.1 Introduction
The OSD displays Closed Captioning (EIA708
specification) or other character data and menus
on a TV screen.
Each row can be defined through three different
Display configurations:
– Serial mode: each character is defined by an 8-
– Basic parallel mode: each character is defined
– Extended parallel mode: each character is de-
8.5.2 General Features
bit word which provides the character address
into the Font ROM memory. Some codes are re-
served for color controls and do not address any
character description. They are displayed as
spaces and as a direct consequence are active
on a “word” basis. This mode fully supports the
Closed Captioning format.
by a 16-bit word which provides the character ad-
dress in the Font ROM memory and its color at-
tribute. This mode is called “parallel” as the
colors are definable on a “per character” basis.
fined by a 24-bit word which provides the charac-
ter address in the Font ROM memory and its
color and shape attributes. This mode is called
“parallel” as the attributes are definable on a “per
character” basis.
50/60 Hz and 100/120 Hz* operation
525/625 lines operation, 4/3 or 16/9 format
Interlaced or progressive scanning
18x26 or 9x13 character matrix user definable in
ROM. Both matrixes can be mixed.
Up to 63 characters per row
7 character sizes in 18x26, 4 in 9x13
512 possible colors in 4x16-entry palettes
8 levels of translucency on Fast Blanking
Serial character mode supporting Closed
Captioning format
Basic Parallel Mode for character based color
definition
Extended parallel mode for character based
color and shape definition
Mouse pointer (user definable in ROM)
Rounding,
scrolling, italics, and various underlining modes
fringing,
shadowing,
flashing,
- ON SCREEN DISPLAY CONTROLLER (OSD)
Definition of Terms used in this Chapter
– Pixel: minimum displayed element that the Dis-
– Dot: a dot defines the displayed element which
8.5.3 Functional Description
All characters are user definable by masking the
Font ROM content (except the one corresponding
to code 00h which is reserved for test). Two differ-
ent matrixes can be used and mixed:
– 18x26 character matrix
– 9x13 character matrix
The hardware display system has the capability of
displaying one character row and requires the
CPU to update the next display buffer prior to dis-
playing the next row. Using a real time routine, the
On Screen Display supports the display of as
many character rows as the TV screen can physi-
cally handle.
The OSD can display up to 63 characters per row,
depending on the row RAM buffer size (user defin-
able, see
The OSD is also designed to handle a mouse
pointer (see
A smart pixel processing unit provides extended
features such as rounding, fringe, or shadowing
for better picture quality. Other smart function such
as flashing, scrolling, italics, underlining and
mouse pointer allow the designing of a high quality
display application.
The screen insertion of the displayed characters is
fully synchronized by the vertical and horizontal
TV synchronizing signals. The OSD controller
generates the Red, Green, Blue and Fast Blanking
video signals through 8-level DAC outputs. The
Fast Blanking video signal can also be generated
as a digital signal if needed.
*Available on some devices
play Controller can handle. Its vertical physical
size is always one TV line. Its horizontal physical
size is directly linked to the basic clock frequency
(called Pixel clock) which synchronizes the OSD
and is therefore independent of any magnifica-
tion factor which may be applied to the displayed
element.
corresponds to a single bit read from the Font
ROM memory. A dot is represented on the
screen by a "matrix" of pixels. The matrix size de-
pends on the magnification factor applied.
Section
Section
8.5.5.1).
8.5.7).
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