AK8851 Datasheet, PDF (48/80 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

ASAHI KASEI
30. Status Information Function of Internal Operation
The AK8851 has [Status 1 Register] to show the internal status.
Bit Allocation of [Status 1 Register] is as follows.
[AK8851]
Sub Address 0x16
bit 7
bit 6
OVCOL
PKWHITE
bit 5
bit 4
CLKMODE1 CLKMODE0
bit 3
COLKIL
bit 2
FRMSTD
bit 1
VLOCK
bit 0
NOSIG
(1) No-Signal Input Detection
The AK8851 detects no-signal input conditions. When it is detected, the output data becomes Black level ( Y = 0x10,Cb
/ Cr = 0x80 ).
The result is output via the NSIG output pin and [NOSIG]-bit of [Status 1 Register] is also set.
* Output state is shown below.
Status of Signal
Detect Signal
NO Signal
[Status 1 Register][NOSIG]-bit
0
1
NSIG Pin
0
1
(2) VLOCK Function
This bit indicates the synchronous state of input signal. The AK8851 synchronizes its internal operation with the input
signal’s Frame configuration.
For example, if the input signal Frame configuration consists of 524 lines, the chip internals operate in the 524-line
configuration. This is called the VLOCK configuration.
When the input signal configured with 525-Lines per Frame is switched to 524 line signal system, the operation tracks to
the switched signal system. In this case, VLOCK function is unlocked during the tracking time. This un-locked state is
checked by [Status 1 Register].
When the input signal is switched, as when switching channels, it takes approximately 4 Frames until the VLOCK
function is locked.
[VLOCK]-bit
0
1
Status of Synchronization
Synchronized to Input video signal
Unsynchronized to Input video signal
Note
(3) FRMSTD-bit :
This detects the input signal’s Frame configuration. . When a non-standard Frame configuration is detected, this bit is
set to “1”.
[FRMSTD]-bit
Status of Frame Standard
Note
0
Frame Configuration is standard
1
Frame Configuration is non standard
(4) COLKIL-bit :
Indicates that the color killer function is active, since the color signal level is very low.
[COLKIL]-bit
Color killer
0
Color killer is not work (Decoding normally)
1
Color killer is working
Note
MS0244-E-03
48
Confidential
2005 / 07