SPI clock frequency?

[gerard-hm]

Is there a way to drive SPI with a frequency outside the formula:

Code: Select all

80MHz / (pre * n)

?

I would like 12MHz, but the closest I can get is either 11.4MHz or 13.3MHz Is there any way to drive SPI using an outside clock?

I'm guessing not, but wanted to check.

BTW. Can anyone point me to an explanation on why the clock is derived using "pre" and "n" multipliers? Seems like an unnecessary hassle.