AK8855 Datasheet, PDF (30/81 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Decoder

[ASAHI KASEI]
AK8855
Output Interface
The AK8855 supports 3 types of Interfaces.
(1) Camera Interface ( QVGA / CIF / QCIF )
(2) Interface by HD / VD / DVALID ( VGA / QVGA / CIF / QCIF )
(3) 656 Interface ( 601 specification compatible size ( 720 X 480 ))
Timing diagrams of each output mode are shown in each output mode description section.
The AK8855 outputs data ( D [ 7:0 ] ) and output timing signals ( HD / HV, VD / VAF, DVALID , FIELD ) in
accordance with the specified timing diagram only when either of the following conditions is met :
(a) when the AK8855 operation is in sync with input signal,
(b) when the AK8855 cannot establish synchronization with input signal and it is decided that no signal
is input ( Black signal output at default condition ).
During transition from condition (a) to condition (b) or from condition (b) to condition (a), specified data ( D [ 7:0 ])
and output timing signals ( HD / HV, VD / VAF, DVALID, FIELD ) may differ from the one shown in the specified
timing diagram.
(1) Camera Interface
There are 2 types of data interface – “ (1-1) HV & VAF Interface Mode “ and “ (1-2) SAV / EAV Interface Mode “.
In this mode, since shift of synchronization with the input signal is adjusted at the head part of Line, interval
between Lines may fluctuate in some degree.
When an exceptional input signal is decoded, there may be cases where lack of # of Lines and lack of # of
Pixels per Line occur, regardless of operation mode.
At the default value, end of Frame is made at the rising edge of VAF signal, and end of Line is made by HV
signal.
Polarity of VAF / HV / DVALID / CLKO is programmable by Output Control 2 Register ( R/W ) [ Sub Address
0x02 ].
Following timing diagrams show operation examples at HDP = 0, VDP = 0, DVALDP = 0, CLKINV = 1 settings.
Since output is Progressive Output in Camera Interface mode, picture sizes to be handled in this mode are
QVGA / CIF / QCIF / rotated QVGA / rotated CIF.
Definition of SAV / EAV at section (1-2) SAV / EAV Interface Mode is as follows.
Active
VBlank
SAV
0x80
0xAB
EAV
0x9D
0xB6
In SAV / EAV Output mode, HV / VAF signal is not output at default value. It is possible to output by setting
register.
MS0319-E-03
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