Application Note
ANC-6023 for Video Sync Interrupt Generation wave line 1

  Video multimedia applications sometimes require synchronizing with the video vertical sync.   A couple of common examples would be in converting video to streaming video and in MIDI for sound synchronization with a video source.   The adapter video sync input can also be used for signal detection, verification and type identification.   The ANC-6023 provides a BNC connector which allows the designer to input NTSC, or PAL, RS170 level composite or striped video.   The on-board sync separator produces an interrupt upon detection of a vertical sync pulse which is readable on the serial port's Data Carrier Detect (DCD, refered to as RLSD on some systems) or Ring Indicator (RI) line.   The designer can further input the serial port's status register to determine if the interrupt was generated by field 1 or field 2.

NTSC Vertical Sync Interrupt

  The oscilloscope image above shows an NTSC RS-170 level video signal (yellow trace,1) and the RS232 level signal produced by the ANC-6023 sync separator to the serial port DCD line (blue trace,2).   The designer can read the DCD line state or set an interrupt on the serial port to detect the odd/even field edges for synchronization.

wavey line1
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Updated 02/21/09 11:00

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