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AD9984A
0x12—Bit[5] Hsync Input Polarity Override
This bit determines whether the chip selects the Hsync input
polarity or if it is specified. Setting this bit to 0 allows the chip
to automatically select the polarity of the input Hsync. Setting it
to 1 indicates that Bit 4 of Register 0x12 specifies the polarity.
Power-up default is 0.
Rev. 0 | Page 32 of 44
Table 20. Hsync Input Polarity Override Bit
Value
Result
0
Hsync polarity determined by chip.
1
Hsync polarity determined by user (Register 0x12, Bit 4).
0x12—Bit[4] Hsync Input Polarity
If Bit 5 of Register 0x12 is 1, the value of this bit specifies the
polarity of the input Hsync. Setting this bit to 0 indicates a
negative Hsync input polarity. Setting this bit to 1 indicates a
positive Hsync input polarity. Power-up default is 1.
Table 21. Hsync Input Polarity Bit
Value
Result
0
Hsync input polarity is negative.
1
Hsync input polarity is positive.
0x12—Bit[3] Hsync Output Polarity
This bit sets the polarity of the Hsync output (HSOUT). Setting
this bit to 0 indicates a negative HSOUT polarity. Setting this bit
to 1 indicates a positive HSOUT polarity.
Table 22. Hsync Output Polarity Bit
Value
Result
0
HSOUT polarity is negative.
1
HSOUT polarity is positive.
0x13—Bits[7:0] Hsync Duration
This 8-bit register sets the duration of the HSOUT pulse. The
leading edge of the Hsync output is triggered by the internally
generated, phase-adjusted, PLL feedback clock. The AD9984A
then counts a number of pixel clocks equal to the value in this
register. This triggers the trailing edge of HSOUT, which is also
phase-adjusted.
VSYNC CONTROL
0x14—Bit[7] Vsync Source Override
This bit is the active Vsync override. Setting this to 0 allows the
chip to determine the active Vsync source, setting it to 1 uses
Bit 6 of Register 0x14 to determine the active Vsync source.
Power-up default value is 0.
Table 23. Vsync Source Override Bit
Value
Result
0
Vsync source determined by chip.
1
Vsync source determined by user (Register 0x14, Bit 6).
0x14—Bit[6] Vsync Source Select
This bit selects the source of the Vsync for sync processing only
if Bit 7 of Register 0x14 is set to 1. Setting Bit 6 to 0 specifies the
Vsync from the input pin. Setting it to 1 selects Vsync from the
sync separator. Power-up default is 0.
Table 24. Vsync Source Select Bit
Value
Result
0
Vsync from VSYNCx input pin.
1
Vsync from sync separator.
0x14—Bit[5] Vsync Input Polarity Override
This bit sets whether the chip selects the Vsync input polarity or
if it is specified. Setting this bit to 0 allows the chip to
automatically select the polarity of the input Vsync. Setting this
bit to 1 indicates that Bit 4 of Register 0x14 specifies the
polarity. Power-up default is 0.
Table 25. Vsync Input Polarity Override Bit
Value
Result
0
Vsync polarity determined by chip.
1
Vsync polarity determined by user (Register 0x14, Bit 4).
0x14—Bit[4] Vsync Input Polarity
If Bit 5 of Register 0x14 is 1, the value of this bit specifies the
polarity of the input Vsync. Setting this bit to 0 indicates a
negative Vsync input polarity. Setting this bit to 1 indicates a
positive Vsync input polarity. Power-up default is 1.
Table 26. Vsync Input Polarity Bit
Value
Result
0
Vsync input polarity is negative.
1
Vsync input polarity is positive.
0x14—Bit[3] Vsync Output Polarity
This bit sets the polarity of the Vsync output (VSOUT). Setting
this bit to 0 indicates a negative VSOUT polarity. Setting this bit
to 1 indicates a positive VSOUT polarity. Power-up default is 1.
Table 27. Vsync Output Polarity Bit
Value
Result
0
VSOUT polarity is negative.
1
VSOUT polarity is positive.
0x14—Bit[2] Vsync Filter Enable
This bit enables the Vsync filter allowing precise placement of
the Vsync with respect to the Hsync and facilitating the correct
operation of the Hsyncs/Vsync count.
Table 28. Vsync Filter Enable Bit
Value
Result
0
Vsync filter disabled.
1
Vsync filter enabled.