Data Translation DT3152-LS, User Manual

Page: 40 / 214

Chapter 2
24
Variable-Scan Signals (Area-Scan Mode Only)
For variable-scan video signals (area-scan operations only), the
horizontal (line) and vertical (frame) syncs come directly from the
video source. Two inputs are provided on connector J1 to accept
separate horizontal and vertical sync signals. LINE_SYNC (pin 2) is
used to indicate the start of a line. FRAME_SYNC (pin 4) is used to
indicate the start of a frame.
By default, the DT3152-LS uses the rising edge of the external sync
signals to reset the horizontal and vertical counters. In cases where
the video is referenced to the falling edge of the external LINE_SYNC
and FRAME_SYNC signals, you can invert the sync signals on the
DT3152-LS board using software.
A variable-scan acquisition is initiated and controlled like any other
single or multiple frame acquisition.
Figure 8 on page 25 illustrates
variable-scan timing and data storage.