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Sync signal polarity — Parallax Forums

Sync signal polarity

pedwardpedward Posts: 1,642
edited 2013-04-11 21:48 in Propeller 2
Forgive the ignorance, but how is the sync polarity specified in the video routines?

What I read says a negative sync is one where the default state of the signal is positive and goes low. Positive sync being ground normally and going high.

Comments

  • cgraceycgracey Posts: 14,133
    edited 2013-04-11 21:48
    pedward wrote: »
    Forgive the ignorance, but how is the sync polarity specified in the video routines?

    What I read says a negative sync is one where the default state of the signal is positive and goes low. Positive sync being ground normally and going high.

    Bit 0 of the video configuration register can be set to 1 for negative hsync or 0 for positive hsync (VGA mode).

    Here is a great page that shows many VGA modes with their timings and sync polarities:

    http://www.tinyvga.com/vga-timing
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