STV2310 datasheet(45/112 Pages) STMICROELECTRONICS

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STV2310

Functional Description

Data Count (DC) Coding

The Data Count (DC) byte is coded according to the parity protection scheme defined in SMPTE

291M or ITU-R BT.1364 specifications, as applied to 8-bit coded data (i.e. bit 6 is the even parity

check of bits 0 to 5, bit 7 is bit 6 complement to 1). In 8-bit applications, the DC byte gives a value

as a 4-byte group.

The number of the group of 4 User Data Words (UDW) transferred for the corresponding TV line is

given in the DC byte using 6 bits.

Checksum (CS) Coding

The Checksum (CS) byte is coded according to the parity protection scheme defined in SMPTE

291M or ITU-R BT.1364 specifications, as applied to 8-bit coded data.

Bits 6 to 0 are the LSB bits of the result of the sum of the seven LSB bits of DID, SDID, DC and all

UDW bytes (any carry is dropped). Bit 7 is the complement of Bit 6.

User Data Word (UDW) Coding

As 00h and FFh codes are prohibited in ITU-R BT.656 specifications, each data byte is substituted

by a pair of bytes; these two bytes are respectively built with:

● The lower data nibble for the lower nibble of the 1

st byte.

● The upper data nibble for the lower nibble of the 2

nd byte.

Data is transmitted in the same temporal order as for the Hardware Filtering.

The TV line value is also provided to the DOF block to prevent scrambling errors when the ancillary

data flow is re-mixed with the video flow.

User Data Word Filler

As data is coded according to the 8-bit application protocol described in SMPTE 291M and ITU-R

BT.1364 specifications, some extra bytes may be inserted into the User Data Word sequence.

These bytes code the value 80h which is meaningless and is used only to maintain a 4-byte UDW

modularity (in compliance with the above specifications). These meaningless bytes are also used to

maintain the most adequate 4-byte wise data storing format handled by the microcontroller.

When an application is running, it is important that these filler bytes are not processed as valid data

items.

UDW Coding for WST - Teletext B

For World System Teletext (WST) standards, the UDW coding scheme depends on the searched

frame code.

When the searched frame code is the usual code (27h), the two first UDW words code the

Magazine (3 bits) and the Page (5 bits) values. In this case, there is no need to perform a nibble

split on these two words.When the searched frame code is validated with a programmable value, a

split of the two first words is applied (as they may not be necessarily Hamming 8/4 coded).

The above bytes are followed by 80 bytes (respectively 64 bytes in 525/60Hz) resulting of the nibble

split of the 40 bytes (respectively 32 bytes in 525/60Hz) decoded from the current TV ancillary data.

Table 16: Magazine and Page Coding

Bit

5432

Magazine

Byte

Coding

Bit 6

1’s complement

Even parity

check for bits

[5:0]

Always 0

Magazine value

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