AK8850 Datasheet, PDF (59/99 Pages) Asahi Kasei Microsystems – NTSC Digital Video Decoder

ASAHI KASEI
[AK8850]
READ OPERATION OF VBID DATA
To read the VBID data, write “1” to the VBIDRQ-bit. The AK8850 is put into a wait state while VBID data decodes.
Received WSS data is decodecd and after the decoding is complete, ”1” is sent back to VBID-bit of the [ STATUS 2
REGISTER ]. The VBID-bit is usually at “1” after a reset ( it becomes “0” by writing “1” at VBIDRQ-bit ).
The decoded 13-bit data is then written into the [ VBID 1.2 REGISTER ] as shown.
Data in the [ VBID 1.2 REGISTER ] is remains until it is over-written.
* [ VBID 1 REGISTER ]
bit 7
bit 6
VBID7
VBID8
bit 5
VBID9
bit 4
VBID10
bit 3
VBID11
bit 2
VBID12
bit 1
VBID13
bit 0
VBID14
* [ VBID 2 REGISTER ]
bit 7
bit 6
Reserved Reserved
bit 5
VBID1
bit 4
VBID2
bit 3
VBID3
bit 2
VBID4
bit 1
VBID5
bit 0
VBID6
READ OPERATION OF WSS DATA
To read WSS data, write “1” to the WSSRQ-bit, The AK8850 is placed into a wait state while the WSS data decodes.
Received WSS data is decoded and after the decoding is complete, ”1” is sent back to WSS-bit of the [ STATUS 2
REGISTER ].WSS-bit is usually at “1” right after the reset ( it becomes “0” by writing “1” at WSSRQ-bit ).
Then the decoded data is written into the [ WSS 1 REGISTER ] and [ WSS 2 & ASPECT DATA REGISTER ] as shown.
Data in the [ WSS 1 REGISTER ] and [ WSS 2 & ASPECT DATA REGISTER ] is remains until it is over-written.
* [ WSS 1 REGISTER ]
bit 7
bit 6
G2-7
G2-6
bit 5
G2-5
bit 4
G2-4
bit 3
G1-3
bit 2
G1-2
bit 1
G1-1
Bit 0
G1-0
* [ WSS 2 & ASPECT DATA REGISTER]
bit 7
bit 6
bit 5
ASPECT Reserved
G4-13
bit 4
G4-12
bit 3
G4-11
bit 2
G3-10
bit 1
G3-9
bit 0
G3-8
7-4-12 VIDEO ASPECT SIGNAL
This command detects the Video Aspect signal ( refer to the following diagram ) that is superimposed on Line 16 and Line
279 of the Composite signal. The Aspect signal detection is performed by making a decode request which is set by the
[ REQUEST VBI INFO REGISTER ].
After the decoding is completed, a decode complete notification is generated. The decode data is written into the
Aspect-bit of the [ WSS 2 & ASPECT DATA REGISTER ].Aspect-bit data remains until it is over-written.
Video Aspect Signal Outline
Input signal : Composite signal only ( at NTSC / YC input only )
Line : 16^th Line and 279^th Line
Level : 70 +/- 25 IRE
Rising Edge Point : 12.5 +/- 3.2 microsec from HSYNC rising edge ( at 50 % point )
Falling Edge Point : 58.9 +/- 3.2 microsec from HSYNC falling edge ( at 50 % point)
Aspect Bit : Wide at “1”
Normal at “0”
70+/-25 IRE
50%
50%
50%
12.5+/-3.2usec
58.9+/-3.2usec
Rev.0
59
2003/01