
AD9981
Preliminary Technical Data
Rev. 0 | Page 24 of 44
Hexadecimal
Address
0x11
Read and
Write or
Read Only
R/W
Bits
7:0
Default
Value
0010 0000
Register Name
Sync Separator
Threshold
Hsync Control
Description
This register sets the threshold of the sync separator’s digital
comparator.
Active Hsync Override.
0 = The chip determines the active Hsync source.
1 = The active Hsync Source is set by 0x12, Bit 6.
Selects the source of the Hsync for PLL and sync processing. This
bit is used only if 0x12, Bit 7 is set to 1 or if both syncs are active.
0 = Hsync is from Hsync input pin.
1 = Hsync is from SOG.
Hsync Polarity Override.
0 = The chip selects the Hsync input polarity.
1 = The polarity of the input Hsync is controlled by 0x12, Bit 4.
This applies to both Hsync0 and Hsync1.
Hsync input polarity: this bit is used only if 0x12, Bit 5 is set to 1.
0 = Active low input Hsync.
1 = Active high input Hsync.
Sets the polarity of the Hsync output signal.
0 = Active low Hsync output.
1 = Active high Hsync output.
Sets the number of pixel clocks that Hsync out is active.
Active Vsync Override.
0 = The chip determines the active Vsync source.
1 = The active Vsync source is set by 0x14, Bit 6.
Selects the source of Vsync for the sync processing. This bit is
used only if 0x14, Bit 7 is set to 1.
0 = Vsync is from the VSYNC input pin.
1 = Vsync is from the sync separator.
Vsync Polarity Override.
0 = The chip selects the input Vsync polarity.
1 = The polarity of the input Vsync is set by 0x14, Bit 4.
This applies to both Vsync0 and Vsync1.
Vsync input polarity: this bit is used only if 0x14, Bit 5 is set to 1.
0 = Active low input Vsync.
1 = Active high input Vsync.
Sets the polarity of the output Vsync signal.
0 = Active low output Vsync.
1 = Active high output Vsync.
0 = The Vsync filter is disabled.
1 = The Vsync filter is enabled.
This needs to be enabled when using the Hsync to Vsync
counter.
Enables the Vsync duration block. This is designed to be used
with the Vsync filter.
0 = Vsync output duration is unchanged.
1 = Vsync output duration is set by Register 0x15.
Sets the number of Hsyncs that Vsync out is active. This is only
used if 0x14, Bit 1 is set to 1.
The number of Hsync periods to Coast prior to Vsync.
The number of Hsync periods to Coast after Vsync.
Coast Source.
Selects the source of the Coast signal.
0 = Using internal Coast generated from Vsync.
1 = Using external Coast signal from external Coast pin.
0x12
R/W
7
0*** ****
6
*0** ****
5
**0* ****
4
***1 ****
3
**** 1***
0x13
0x14
R/W
R/W
7:0
7
0010 0000
0*** ****
Hsync Duration
Vsync Control
6
*0** ****
5
**0* ****
4
***1 ****
3
**** 1***
2
**** *0**
1
**** **0*
0x15
R/W
7:0
0000 1010
Vsync Duration
0x16
0x17
0x18
R/W
R/W
R/W
7:0
7:0
7
0000 0000
0000 0000
0*** ****
Precoast
Postcoast
Coast and Clamp
Control