AK8855 Datasheet, PDF (25/81 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Decoder

[ASAHI KASEI]
AK8855
Closed Caption / Closed Caption Extended Data / VBID ( CGMS ) / WSS
Closed Caption data, Closed Caption Extended data, VBID ( CGMS ) and WSS signals which are
super-imposed during VBI interval are decoded in the AK8855. Decoded data is written into register.
When Request bits [ bit3 : bit 0 ] of Request VBI Info Register ( W ) [ Sub Address 0x0A] are set, the AK8855
judges that a decode request of each data is made and it is put into data wait condition.
After data is detected and decoded, it informs to the Host, using [ bit3 : bit 0 ] of Macrovision Status Register
that decoding has been completed.
Decoded results are written into Closed Caption 1 Register ( R ) [ Sub Address 0x12 ] / Closed Caption 2
Register ( R ) [ Sub Address 0x13 ], Extended Data 1 Register ( R ) [ Sub Address 0x14 ] / Extended Data
2 Register ( R ) [ Sub Address 0x15 ], VBID / WSS1 Register ( R ) [ Sub Address 0x16 ] / VBID / WSS2
Register ( R ) [ Sub Address 0x17 ] respectively.
Each data is super-imposed on the respective Line as listed below.
CRCC code of VBID data ( CGMS-A ) is decoded and its result only is stored in register.
Signal
Closed Caption
Closed Caption Extended
VBID
WSS
Line
NTSC : Line-21
NTSC : Line-284
NTSC : Line-20/283
PAL : Line-23
Note
525-Line
525-Line
525-Line
625-Line
Configuration of Request VBI INFO Register is as follows.
Sub Address 0x0A
bit 7
bit 6
bit 5
bit 4
bit 3
Reserved Reserved Reserved Reserved Reserved
Default Value
0
0
0
0
0
bit 2
VBWSRQ
0
Default Value: 0x00
bit 1
bit 0
EXTRQ
CCRQ
0
0
Configuration of Status Register is as follows
Sub Address 0x10
bit 7
bit 6
bit 5
bit 4
VBWSSDE
T
EXTDET
CCDET
AGCSTS
bit 3
CPLLLCK
bit 2
PKWHITE
bit 1
COLKILST
bit 0
NSIG
Information Read-Out Flow during VBI interval is shown below.
Start
[ Request VBI Info Register ]
xxRQ-bit = 1
( Decode Request )
Closed Caption: CCRQ-bit
Closed Caption Extended : EXTRQ-bit
VBID/WSS: VBWSRQ-bit
[ Status Register ] Read
( Verification of decode completion )
( Corresponding bit
is “1” to the
request ? )
Yes
( Read-out of the corresponding
data register to the request )
No
Closed Caption: CCDET-bit
Closed Caption Extended : EXTDET-bit
VBID/WSS: VBWSDET-bit
Closed Caption: [Closed Caption 1/2 Register]
Closed Caption Extended : [Extended Data 1/2 Register]
VBID/WSS: [VBID/WSS 1/2 Register]
MS0319-E-03
25
2004 / 11