Memory clock for UNC20 and UNC90


I want to try the UNC90 in an in-production board I’ve designed for the UNC20. In order to access an on-board memory-mapped CAN controller, I need to configure
the UNC90’s CS4 chip select signal to mimic the timing of the UNC20’s CS4.

I’ve gone through the NS7520 and AT91RM9200 manuals, and I think I know what to do, but to calculate the timings I need to know the following two magic numbers:

a) The frequency of BCLK in the UNC20. Is it 55MHz, or is it divided to some other value?

b) The frequency of SCK in the UNC90.

Thanks for your help,

Nacho de los Ríos