On May 31, 2011, at 12:17 AM, IV3YNB op. Matteo wrote:

> the trouble now comes when I have to manage frequency value
> and get it in 32bit.
>
> The formula is M =3D (f0 * 2^32)/fc

You'll have to re-arrange that formula to get this to work in most C =20
compilers (or most other languages), since most values of f0*2^32 will =20
exceed 32 bits...

If Fc is 50MHz, you can do (f0 * (2^32/128) / (Fc/128)
(128 is the greatest common factor of 2^32 and 50e6)
More math tricks may be needed depending on the range and required =20
accuracy of f0, but the general principle is DON'T LET INTERMEDIATE =20
RESULTS EXCEED THE VARIABLE SIZE.

BillW

--=20
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