OM8373 datasheet(29/108 Pages) PHILIPS

29 / 108 page

2004 Jan 15

Philips Semiconductors

Tentative Device Speciﬁcation

TV signal processor-Closed Caption

decoder with embedded

µ-Controller

OM8373; OM8378

• SFR flags indicating reception of US Line 21 Data

Services.

Analogue to Digital Converter

The CVBS input is passed through a differential to single

ended converter (DIVIS), although in this device it is used

in single ended configuration with a reference.The

analogue output of DIVIS is converted into a digital

representation by a full flash ADC with a sampling rate of

12MHz.

Multi Rate Video Input Processor

The multi rate video input processor is a Digital Signal

Processor designed to extract the data and recover the

clock from the digital CVBS signal.

Data Standards

The data and clock standard that can be recovered is

shown in Table 8 below:-

Data Capture Timing

The Data Capture timing section uses the Synchronisation

information extracted from the CVBS signal to generate

the required Horizontal and Vertical reference timings.

The timing section automatically recognises and selects

the appropriate timings for either 625 (50Hz)

synchronisation or 525 (60Hz) synchronisation. A flag

TXT12.Video Signal Quality is set when the timing section

is locked correctly to the incoming CVBS signal. When

TXT12.Video Signal Quality is set another flag

TXT12.625/525 SYNC can be used to identify the

standard.

Acquisition

Closed Caption Acquisition

The US Closed Caption data is transmitted on line 21 (525

line timings) and is used for Captioning information, Text

information and Extended Data Services. Closed Caption

data is only acquired when TXT21.CC ON bit is set.

Two bytes of data are stored per field in SFRs, the first bye

is stored in CCDAT1 and the second byte is stored in

CCDAT2. The value in the CCDAT registers are reset to

00h at the start of the Closed Caption line defined by

CCLIN.CS<4:0>. At the end of the Closed Caption line an

interrupt is generated if IE.ECC is active.

The processing of the Closed Caption data to convert into

a displayable format is performed by Software.

DISPLAY

The display section is based on the requirements for US

Closed Caption. There are some enhancements for use

with locally generated On-Screen Displays.

The display section reads the contents of the Display

memory and interprets the control/character codes. Using

this information and other global settings, the display

produces the required RGB signals and Video/Data (Fast

Blanking) signal for the TV signal processing.

The display is synchronised to the TV signal processing by

way of Horizontal and Vertical sync signals generated

within the TV processor. From these signals all display

timings are derived.

Display Features

• US Closed Caption features and Enhanced OSD

modes.

• Normal, Double Height, Double Width and Double size

characters.

• Scrolling of display region.

• Variable flash rate controlled by software.

• Globally selectable scan lines per row 9/10/13/16/18.

• Globally selectable character matrix (HxV) 12x9, 12x10,

12x13, 12x16, 12x18, 16x9, 16x10, 16x13, 16x16 and

16x18.

• Globally selectable horizontal and vertical character

spacing.

• Italics, Underline and Overline.

• Soft Colours using CLUT with 64 colour palette.

• Fringing (Shadow) selectable from N-S-E-W direction.

• Fringe colour selectable.

• Contrast reduction of defined area.

• Cursor.

• Special Graphics characters with two planes, allowing

four colours per character.

• 16 Software re-definable On-Screen Display characters.

Display Conﬁguration

The display section can be configured as a maximum of 16

rows with up to 48 characters per row. Both the Character

matrix, and TV lines per row can be defined. There is an

option of 9, 10, 13, 16 & 18 TV lines per display row, and

a Character matrix (HxV) of 12x9, 12x10, 12x13, 12x16,

12x18, 16x9, 16x10, 16x13, 16x16 & 16x18. Additionally,

up to 4 pixels of character spacing may be introduced

between characters in the horizontal direction and up to 7

TV lines may be inserted between display rows.

Data Standard

Clock Rate

Closed Caption

500 KHz

Table 8

Data Slicing Standard

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