I have a project, using two MCU: MC9S12UF32 and MC9S08AW60. I need to make them work at full bus frequency: 30MHz and 20MHZ respectively.
I could use MC9S08 internal self-clocked source but I need high clock accuracy.
Can I use two oscillator crystals of 12MHz and 4 MHz in the same PCB without inducting noise?
Or I can use the ECLK signal, in expanded mode, to drive the 8-bit MCU? If I do so, could I use 9S12 ECLK at 30MHz or 20MHz, driving 9S08 MCU in EXTAL pin at 15MHz or 20MHz bus frequency respectively?
I want also to use external memory, at full speed (30MHz bus frequency) if I can.
What do you recomend?