Flash operating and RAM operating time

Hiroyasu Tazawa1

Hi,Everyone

I need your help.
I use Concerto F28M35xxx.

We compare Flash execution speed with Shared RAM execution speed on M3.
In result, Shared RAM Operation time is faster than Flash operation time.

I do not know why this result.
This reason why I understand Flash connect I-code bus and D-code bus to CPU.
but Shared RAM does not connect there.

This understand is correct??

Best Regards
Hiroyasu

over 9 years ago

0 Vamsi Gudivada over 9 years ago

TI__Guru* 84475 points

Hiroyasu,

Flash memory needs additional wait-states at higher operating frequencies and hence it takes additional cycles to execute code out of Flash when compared to that of RAM.

Thanks and regards,
Vamsi

0 Hiroyasu Tazawa1 over 9 years ago in reply to Vamsi Gudivada

Guru 12350 points

Hi,Vamsi

Thank you for your reply.
and Sorry, I have a mistake.

Flash speed is faster than Shared RAM speed on M3.
What do you think about?

Best Regards
Hiroyasu

0 David M. Alter over 9 years ago in reply to Hiroyasu Tazawa1

TI__Guru 61235 points

Hiroyasu,
I have seen this behavior before on Cortex-M devices (flash execution faster than RAM execution). I think there is only one bus accessing the RAM. If you have code and data in the RAM, you bottleneck there.

- David

0 Hiroyasu Tazawa1 over 9 years ago in reply to David M. Alter

Guru 12350 points

Hi,David

Thank you for your reply.
I got it.

Best regards
Hiroyasu

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Flash operating and RAM operating time