Datasheet

Table Of Contents
ADV7188
Rev. A | Page 57 of 112
The checksum value of B8 to B0 is equal to the nine LSBs
of the sum of the nine LSBs of the DID, SDID, and dc, as
well as all UDWs in the packet. Prior to the start of the
checksum count cycle, all checksum and carry bits are
preset to 0. Any carry resulting from the checksum count
cycle is ignored.
EP
. The MSB, B9, is the inverse of EP. This ensures that
restricted Codes 0x00 and 0xFF do not occur.
Line_number [9:0]. The number of the line that immediately
precedes the ancillary data packet. This number is as per the
numbering system of ITU-R BT.470, ranging from 1 to 625
in a 625-line system and from 1 to 263 in a 525-line system.
Note that the line on which the packet is output differs from
the line on which the VBI data was sliced due to the vertical
delay through the comb filters.
Data Count. The data count specifies the number of UDWs
in the ancillary stream for the standard. The total number
of user data-words is four times the data count. Padding
words can be introduced so that the total number of UDWs
is divisible by 4.
Table 71. Ancillary Data in Nibble Output Format
Byte B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Description
0 0 0 0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1 1 1 1
2 1 1 1 1 1 1 1 1 1 1
Ancillary data preamble.
3
EP
EP 0 I2C_DID6_2 [4:0] 0 0
DID (data identification
word).
4
EP
EP I2C_SDID7_2 [5:0] 0 0
SDID (secondary data
identification word).
5
EP
EP 0 DC [4:0] 0 0 Data count.
6
EP
EP padding [1:0] VBI_DATA_STD [3:0] 0 0 ID0 (User Data-Word 1).
7
EP
EP 0 Line_number [9:5] 0 0 ID1 (User Data-Word 2).
8
EP
EP Even_Field Line_number [4:0] 0 0 ID2 (User Data-Word 3).
9
EP
EP 0 0 0 0
VDP_TTXT_TYPE
[1:0]
0 0 ID3 (User Data-Word 4).
10
EP
EP 0 0 VBI_WORD_1 [7:4] 0 0 User Data-Word 5.
11
EP
EP 0 0 VBI_WORD_1 [3:0] 0 0 User Data-Word 6.
12
EP
EP 0 0 VBI_WORD_2 [7:4] 0 0 User Data-Word 7.
13
EP
EP 0 0 VBI_WORD_2 [3:0] 0 0 User Data-Word 8.
14
EP
EP 0 0 VBI_WORD_3 [7:4] 0 0 User Data-Word 9.
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
n − 3 1 0 0 0 0 0 0 0 0 0
n − 2 1 0 0 0 0 0 0 0 0 0
Pad 0x200. These
padding words may not
be present depending
on ancillary data type.
User Data-Word XX.
n − 1
B8
Checksum 0 0 CS (checksum word).