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Arduino and composite colour video

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dr pepper

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Has anyone played with this?
I'd like to experiment generating colour bars with the arduino.
B&W has allready been done, and colour on some other chips.
Timer 2 could be used to generate a digital output for the colour burst and chrominance / saturation signal, that is if a tv would accept squarewave chrominance, and if pulse width would work for the saturation signal.
And to generate luminance say of 4 levels 2 other pins could be used with a simple r-2r ladder, this and the chrominance part can be mixed and buffered with a tranny, ok mixing levels would need to be carefully arranged.
Ok the chip might not be able to do a lot else, but this is an interesting idea to play with for some.
Things would get a little more complex for pal, but ntsc shouldnt be so hard.
 

Nigel Goodwin

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Use the chip to generate RGB signals, and an RGB/PAL(NTSC) chip to generate the composite video - I have a colour bar generator that uses a PIC to do just that.
 

dr pepper

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Well the idea was to get to grips with colour encoding/decoding, however following up your suggestion I found analogue devices do the ad724, which does as you say accept RGB and individual sync, then converts that to pal video, that would kinda take out a whole load of headache coding wise, wouldnt even need to mess about with vert sync, I did that in asm with the pic and it was really hard to get my vintage tv to work with it.
Might make a colour bar gen to go with my homebrew crt checker.
 

dr pepper

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Dont worry it doesnt stuff mains on the cathode or anything mad like that, and its not a bulb bopper.
I didnt build it, it was given to me by a tv repair shop I used to be freindly with, I think he built it from the old 'televison' magazine, and it was a while back a couple of the caps have failed since I've had it.
One good thing about it is the filament voltage is continuously adjustable.
 
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