How about the DMIPS/MHz of the S12XE ?

[renjunma]

Hello,

Could anyone tell me how about the DMIPS/MHz or MIPS/Hz of the S12XE ?

I have checked some document, but it only mention the performance about XGATE.

Thanks in advance.

[iggi]

Hi

The best value that can give you more of reference is the Max Bus Frequency. In the case of S12(X) devices, the architecture of device make that the instructions take different time to execute. Some instructions take 1 bus cycle, others can take more than 5 bus cycles depending on the complexity of the instruction. So it's not very easy to just list a value to evaluate the cpu performance (MIPS value).

If you would like to check the execution time of HCS12X instruction, you can find the information in Table A-2. of S12XCPURM at http://www.freescale.com/files/microcontrollers/doc/ref_manual/S12XCPUV2.pdf, which can give you a more precise execution time for each instruction. For example, INCA needs 1 bus cycle while EDIV needs 11 bus cycles, which means the MIPS value for INCA is 50 and EDIV is about 5 while CPU works at Max Bus Frequency .

The S12XE can work on 50MHz bus clock. One instruction typically takes 1-12 bus cycles. The most often used instructions take 2-4 cycles. This means 0,25-0,5MIPS/MHz for main CISC core.

The XGATE co-processor is a built in RISC core with one instruction per bus cycle, so there we have 100 MIPS.

Hope this helps.

Regards,

iggi

[renjunma]

Hello,

Thank you very much for you detail reply.

We can understand that's not easy to judge it by different instruction cycle.

Could you help us check whether there's any bench mark you have run for this product. Coremark ? Or any others.

[iggi]

Well, i'm  not aware of any available benchmark. There is a Dhrystone benchmark done for most of our processors, but not sure if this was done for S12XE product line. If yes, then this might be information for internal use only.