AVR-Chat

For an ARM based implementation using a digital still
video source, see my project "Video Frame Grabber"
among the DE entries of Luminary ARM contest.

The URL is
http://www.circuitcellar.com/designstellaris2006/winners/DE/LM1719.htm

Cheers,
Samir.

--- Jim Wagner <jim_d_wagner@applelinks.net> wrote:

> On Mon, 11 Jun 2007 02:48:22 -0000
>  "kernels_nz" <kernels@slingshot.co.nz> wrote:
> > Hi guys, I have a curly one, any creative
> suggestions
> > would be
> > appreciated.
> > 
> > Im interested in digitzing a B/W video waveform
> from a
> > standard CMOS
> > security camera, im only really interested in one
> line of
> > video but
> > the conversion time of the average AVR A2D is
> around
> > 13-50us but the
> > whole video frame is around 50us. 
> > 
> > I know I can overclock the AVR A2D to around 1MHz,
> but
> > that still
> > would only give 4 conversions per video frame.
> > 
> > So, a few ways that I could see around the problem
> is:
> > 
> > 1. Faster external ADC -> Not ideal because it
> adds cost,
> > componets
> > and it's hard to get hold of Megasample ADCs.
> Also,
> > having a fast
> > external ADC is useless unless you can communicate
> with
> > it at super speed.
> > 
> > 2. Slow down "time" somehow so that I buffer a
> frame of
> > video
> > "somehow" and convert it at my leasure using the
> inbuilt
> > ADC. <- This
> > method requires "magic" and im not sure what type
> ? maybe
> > someone has
> > come across some way of doing this ?
> > 
> > 3. Use some of the "line" cameras that allow me to
> clock
> > the video
> > data out pixel by pixel. <- I can do this, and we
> even
> > have the
> > cameras available @ work, but I would prefer to
> use a
> > off-the-shelf
> > cheap video camera.
> > 
> > Any other ideas?
> > 
> > Thanks !
> > 
> > Hein B
> > Auckland, New Zealand.
> > 
> 
> No, one video line is about 64us (very close to same
> for
> NTSC and PAL).
> 
> Philips (now NXP) makes a whole bunch of video
> ditizer ICs.
> They are very nice and do the synchronizing, etc for
> you.
> You would need a video sync detector for any
> digitizer
> solution.
> 
> The simplest, by far, would be a line sensor, I
> think.
> Within limits you can clock it at any rate you want.
> 
> 
> Jim
> 
> 
>
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