Z86230 Datasheet, PDF(36/61 Page) Zilog, Inc. – ADVANCED VIOLENCE BLOCKING AND NTSC 21 XDS

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Z86230 Datasheet, PDF (36/61 Pages) Zilog, Inc. – ADVANCED VIOLENCE BLOCKING AND NTSC 21 XDS

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CONTROL REGISTERS

XDS DATA RECOVERY

TABLE 28. XDS DATA EXTRACTION EXAMPLE FILTER SETTINGS

{WRITE Command,

Filter Code}

XDS Filter Output

{C5,41}

{C5,61}

{C5,1F}

{C5,01}

{C5,28}

{C5,9F}

All In Band; Current Class packets recovered.

Program Rating; Current Class packets recovered. This

ï¬lter may be used for Program Blocking Data Packet

Recovery.

All XDS packets recovered.

All Current Class packets recovered.

Time information recovered. This ï¬lter extracts the

Time of Day (TOD) and Local Time Zone (LTZ) packets

from the Miscellaneous Class data.

This ï¬lter may be used to implement Auto Clock-

Setting in TVs, and VCRs.

VCR Information recovered. This ï¬lter selects TOD, LTZ,

Net ID, Local Call Letters, Impulse Capture, Tape Delay,

Composite 2, and Out-of-Band Channel Number

packets for recovery.

6.2.1 Filtered XDS Data Format

Filtered XDS data is output from the Z86230 in the order it is received on Line 21.

In other words, think of the Z86230 XDS ï¬lter function as creating a new, smaller

stream of XDS data packets. This new data stream looks exactly as though the

Class and Type speciï¬ed in the XDS Filter Register (05h) are the only data

encoded on Line 21 of Field 2. The ï¬ltered data output from the Z86230 is in full

compliance with EIA-608 speciï¬cations for XDS data streams (headers and con-

trol codes intact). Refer to the NOTE paragraph on the next page for a special

exception to this rule.

XDS data and header information (including START, CONTINUE, and END com-

mands) are passed through the ï¬lter for the XDS Class and Type speciï¬ed in the

XDS Filter Register. All other Line 21 data is ï¬ltered out. This data does not out-

put or generate a data available ï¬ag (DAV) in the Serial Status Register (SSR).

To properly read ï¬ltered XDS data from the Z86230, the master device must ï¬rst

write the XDS Filter Register (05h) with its required XDS Class and Type infor-

mation. For example, in the Z86230, in order to extract ONLY the Line 21 Pro-

gram Rating information, the master must write the value 61h to the XDS Filter

DAV = 1.

As soon as DAV = 1, the master may initiate a 3-byte READ in RBS Read Bank 0

mode (XDS data bytes always arrive in pairs, so it is safe to read the ï¬rst 2 bytes

of read bank 0 when DAV = 1 in the SSB). A 3-byte READ always yields two data

bytes, which in this case are the ï¬rst 2 bytes of the Current Class, Program Rating

Type XDS data stream encountered on Line21, Field 2. The master device must

then interpret those 2 bytes according to EIA-608 speciï¬cations for Current Class,

Program Rating Type data. Refer to EIA-608 for the appropriate data formats.

Z86230âPRELIMINARY

PS000400-TVC0499

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