Performance comparison MC56F82xxx vs. MC56F81xxx

[JPE]

Hi,

according to the data sheets and other manuals, the MC56F82xxx and MC56F81xxx should provide similar performance (100 / 50 MHz core frequency).

But our initial tests show, that the execution time for the same code looks to be 25-30% longer on our device, after replacing a 82748 with a 81748.

I've checked, that the "fast mode" is active on the 81748 and have no other clue, why there is this difference for the execution time.

Do you have any suggestions, what else to check or what could be causing this difference between the 82748 and the 81748?

@xiangjun_rong

[xiangjun_rong]

Hi, Joern,

I agree with you that the MC56F82xxx and MC56F81xxx should have similar performance. Regarding the performance difference, I suppose that the CPU_CLK clock tolerance leads to the performance difference. Do you use internal 8MHZ clock or external 8mHZ crystal or clock source?

Can you output the CPU_CLK to CLKO pin  and compare the clock frequency via oscilloscope?

BR

XiangJun Rong