AK8851 Datasheet, PDF (47/80 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

ASAHI KASEI
27.Blue-Back Function
The Output can be set to Blue-Back mode by setting a register via the host CPU.
The output code at Blue-Back mode is
Y=41,Cb=240,Cr=110
[AK8851]
The Blue-Back mode set is done by [BLUEBACK]-bit of [Control 2 Register]((R/W)[Sub Address 0x09].
* Bit allocation of [Control 2 Register] is as follows.
Sub Address 0x09
bit 7
bit 6
Reserved STUPATOFF
bit 5
ERRHND1
0
0
0
bit 4
bit 3
ERRHND0 Reserved
Default Value
0
0
bit 2
BLUEBACK
0
Default Value : 0x00
bit 1
bit 0
DPAL1
DPAL0
0
0
* [BLUEBACK]-bit :
Output code becomes blue by setting this bit.
[BLUEBACK]-bit
Output Code
0
Normal Decode Process
Blueback code output
1
Y = 41
Cb = 240
Cr = 110
Note
28.Phase Compensation Function of PAL Decoder
This is a phase compensation function for each Line when decoding PAL signals.
Correlation detection is used for phase error compensation and it is applicable only for correlated samples. For NTSC
signals, a color averaging process between Lines is performed.
This function is set by [Control 2 Register](R/W)[Sub Address 0x09].
Sub Address 0x09
bit 7
bit 6
Reserved STUPATOFF
bit 5
ERRHND1
0
0
0
bit 4
bit 3
ERRHND0 Reserved
Default Value
0
0
bit 2
BLUEBACK
0
Default Value : 0x00
bit 1
bit 0
DPAL1
DPAL0
0
0
[DPAL1:DPAL0]-bit :
* PAL Phase Error compensation is set by [DPAL]-bit.
[DPAL1:DPAL0]-bit
function
00
Adaptive PAL Phase compensation is on
01
PAL Phase compensation is on ON
10
PAL Phase compensation is on OFF
11
Reserved
Note
29. Digital Pixel Interpolator
In order to align Vertical Pixel positions, a Digital Pixel Interpolator is used in the AK8851. When the auto mode (default
state) of the Pixel Interpolator is selected by [INTPOL1:INTPOL0]-bit of [Control 1 Register], ON/OFF control of the
interpolator is automatically switched as follows which is linked with [CLKMODE1:CLKMODE0]-bit set.
Line-locked clock mode : OFF
Frame-locked clock mode : ON
Fixed clock mode
: ON
[ INTPOL1:INTPOL0]-bit
00
01
10
11
Auto
ON
OFF
Reserved
Pixel Interpolator
MS0244-E-03
47
Confidential
2005 / 07