I am trying to generate a stable 4.43361875 MHz clock (i.e. PAL colourburst) synchronised to the colourburst of a PAL video signal.
In a PAL signal the colourburst is provided for only about 8-10 cycles near the beginning of each line. So, I need a way to start the oscillator immediately on the rising edge of this clock source so they are in phase with each other. Once started, it can free run to keep the colour reference frequency accurate for other parts of the system.
I've thought about using a low end PIC24EP64GP202 to do the timing stuff (thanks to its onboard PLL and easy availability), but I can't think of a way to get its oscillator to start on a rising edge input. Is it perhaps possible to "pulse" the crystal with this incoming colour burst (so it rings for a few cycles) and then let the PIC take over? Perhaps it's possible, once running, to change the phase of the system clock?
I've noticed the PIC has a rated 1024 cycle start-up time, but I wonder if that's simply the lock-out period in which the processor doesn't get any clocks but the oscillator still runs fine.