I am missing something here. The documentations states that in order to use USB, the output of the PLL must be 48MHz or 96MHz or 192MHz plus or minus 0.25%. None of which are dividable by the crystal 18.432MHz shipped with the development kit. Does the USB really need one of these three PLL frequencies or am I doing my math wrong?
I assume you are using an AT91SAM7, you can not have 48MHz, the best I could do is 48054858Hz.
PLL divider = 14
Multiplier = 72
(18432000 / 14) * (72 + 1) = 96109714 (PLL frequency)
There are other values for the Multiplier and Divider that would give a better result but those would make the VCO work below the 1MHz minimum frequency.