At 05:34 PM 1/14/03 +0000, you wrote:
>Hi,
>
>I have previously used PIC microcontrollers for a small video related
>product. I have always used the PIC16F84
>
>I am now looking to superimpose some graphics onto a video signal using a
>PIC, a cross hair graticule. The problem is that the resolution required
>for the graphics is ~100ns, so I would want to clamp the video for 100ns.
>With a 16F84A @20MHz the fastest instruction cycle will be 200ns.
>
>I realise that I could use one of the faster pic 18 series running at
>40Mhz to reduce the instruction cycle, thus allowing me to get closer to
>the 100ns resolution. I have never used any of this series before. Can
>anyone tell me of any major problems that moving to these higher level
>devices my create?
>
>Or is anyone aware of any techniques to get closer to a 100ns resolution?

You could just hang a one-shot onto your output to get a 100ns pulse width,
but the resolution of the timing (the horizontal position) can only be
selected in 200ns increments with a 20MHz PIC unless you use trickery
like selectable delays or whatever.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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