BitFlow NEO-PCE-CLB, Hardware Reference Manual

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Generation of Acquisition Windows The Neon
NEO-2-10 BitFlow, Inc. Version G.5
Figure 2-4 Generation of the Horizontal Active Window, HAW
2.4.2 The Vertical Active Window, VAW
The Vertical Active Window (VAW) is a square wave that defines the portion of the
frame that will be acquired vertically. VAW can span less than the whole camera
frame, if we want to acquire only a portion of that frame. The size of the VAW is deter-
mined by a single number, the Active Lines Per Frame (ALPF). The ALPF is defined as
the number of HAW periods during which the VAW is active. The ALPF field is pro-
grammed in CON17. The 17 bits define the maximum VAW as minimum 128K lines.
The total number of lines per frame that will be acquired can be different than the
ALPF. For a dual tap camera that supplies odd-even lines for example, the total num-
ber of lines acquired will be twice the ALPF as in the period of one HAW the camera
supplies two lines.
The size of the VAW is on an arbitrary boundary. The start in time of the VAW can
come from two sources, depending on the setting of the VAW_START bit:
The VSTART bit in the VCTAB, if VAW_START = 1.
The start of FEN, if VAW_START = 0.
Data will be acquired in the window defined by the HAW and the VAW
Figure 2-5 shows the controls that generate the VAW.
Hor i zontal
CTAB
2:1
MUX
HAW
Generator
ACPL, TRIM
LEN
HAW_START
HSTART HAW