Re: Simple crystal (4.43MHz - PAL) oscillator + PLL multiplier circuit wanted. - Article 2029 - go-pugleaf

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Re: Simple crystal (4.43MHz - PAL) oscillator + PLL multiplier circuit wanted.

#2029

From: David L. Jones
Date: Mon, 05 Mar 2007 11:27

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On Mar 5, 7:47 pm, Lionel <use...@imagenoir.com> wrote:
> Per the subject line. I want to experiment with direct PAL video
> generation from a microcontroller, with the minimal number of parts.
> I'm thinking that a good starting place might be to use a CPU clock
> that's based on the PAL subcarrier frequency (4.43MHz) multiplied with
> a PLL+VCO+Divider to give me phase reference points, & directly
> generate the composite colour signal via an R2R ladder.
>
> So, some questions:
>
> 1) Is this a reasonable concept? (I'm comfortable with per-cycle level
> timing & coding)

A few people have had (limited) success with direct composite PAL
video generation directly from a micro, like this one:
http://www.rickard.gunee.com/projects/video/pic/gamesys.php
Ordinary quality, but shows that the minimum parts count is a PIC and
two resistors!
Much faster micros are available would obviously do a bit better than
the PIC.

Dave :)

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From: "David L. Jones" <altzone@gmail.com>
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Subject: Re: Simple crystal (4.43MHz - PAL) oscillator + PLL multiplier circuit wanted.
Date: 5 Mar 2007 03:27:53 -0800
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