hi,
I'm working a composite video signal generator (fancy name for a video synth)
the idea is to input modulated signals into a video encoder (AD725) and output it on the tv through composite procotole.
I need to generate Hsync and Vsync (or simply "composite sync") for the AD725 to function properly.
My idea for the first experiment was to use an LM1881 extracting timing imformation from an old PAL Playstation. However for the final project I'd need to make a stand alone sync generator for obvious reasons.
Considering the high number of tv, I'm pretty sure that some manufacter designed chips for this very task. However, no ideas about references, do you have some ?
Another idea was to use a µC clocked with the same 14.7Mhz crystal (needed for the AD725) and generate all the pulses with I/O pin changes (the AD725 is TTL compatible) But I'm not sure if the atmega could be time precise with all the changes.
The others tricky part : the RGB signals need to be put at 0V when the color burst occurs (in the AD725) for a 2.2µS period. Once again I thought about controlling this with the µC.
Anyway, a dedicated chip for all this could be really nice and save so much time.
do you have any experience with PAL tv protocol ?
Any experience with the AD725 ?
how to generate the sync pulses ?
Any advices , ideas ?
thanks