On 13/07/2011 10:10, dipten wrote:
> However the problem now is: how to synchronize with some arbitrary input
> waveform or arbitrary frequency (changed to square wave using comparator)=
..
>
> Can any one please suggest me a scheme?

Count between two rising (or falling) edges to measure very low frequencies=
..
Count using onboard HW counter and read & reset at fixed time interval=20
to measure higher frequencies

Use XOR between your current O/P (internal Squarewave at 0 or 90=20
degrees) 1 or 0 and software low pass filter to retard or increase the=20
start time of scanning the 256 table.

Read up on how PLLs work.
--=20
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