402-00005-00
Registers
3–36
Rev 02; February 8, 2002
Use the following formula to calculate VOFF:
VOFF = number of lines from FEN to the start of active video – 1
VOFF
Function
0
Start loading memory 1 line after FEN edge
1
Start loading memory 2 lines after FEN edge
2
Start loading memory 3 lines after FEN edge
3
Start loading memory 4 lines after FEN edge
. . .
. . .
1023 (0x3FF)
Start loading FIFO 1024 lines after Vsync edge
3.4.5.2 Vertical Active (VACT) R/W
VACT defines the number of valid lines loaded by the Programmable Window Generator (PWG). The 12-bit value is
the vertical line count that stops loading data into the memory frame.
The PWG vertical counter starts counting on selected edge of FEN and stops counting and loading when the last line
is loaded into the memory. VACT is the vertical count of the last valid line (stop counter). VOFF is the vertical count
of the first valid line (start loading memory). The memory loads all lines between VOFF and VACT.
Use the following formula to calculate VACT. For interlaced images use number of lines per field and for non-inter-
laced use number of lines per frame.
VACT = # lines from FEN to the end of active video – 1
VACT
Function
0
End loading memory 1 line after FEN edge
1
End loading memory 2 lines after FEN edge
2
End loading memory 3 lines after FEN edge
3
End loading memory 4 lines after FEN edge
. . .
. . .
4095 (0xFFF)
End loading memory 4096 lines after FEN edge
3.4.5.3 15-Pin TTL Trigger 0 Status (EXTRIGSTAT0_15) R-O
This read only bit reflects the status of the TTL Trigger 0 input on the 15-pin video connector.
EXTRIGSTAT0_15
Status
0
Trigger input is 0
1
Trigger input is 1
3.4.5.4 TTL Trigger 1 Status (EXTRIGSTAT1) R-O
This read only bit reflects the status of the TTL Trigger 1 input on the 26-pin video connector.
EXTRIGSTAT1_26
Status
0
Trigger input is 0
1
Trigger input is 1
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