Execution from flash very slow.

Narasimha Prasad

Hello,

I'm working on 3 phase rectifier control on the F28335. When I run the program from RAM, there is no problem, but when I run from flash, execution speeds are terrible. I'm noticing a 200% drop in speed. I'm following the SPRA958I application note. Please find the project at https://www.dropbox.com/sh/gmdoqwgqfxjrbim/CxcOck6lMB . I'm switching the rectifier at 20kHz and running the ControlISR at the same speed, but when I run it from FLASH, the ControlISR falls to 80Hz.

Please let me know what I am doing wrong. I have been unable to fix the problem for quite some time.

Thank you and best regards

over 12 years ago

0 Gautam Iyer over 12 years ago

Guru 192875 points

Hi Narasimha,

I'm noticing a 200% drop in speed. I'm following the SPRA958I application note.

Surely, there's some other issue because for some conditions flash is slower but not as slow as you describe. An immediate solution for you would be to copy your ControlISR section to RAM using this doc:

5807.Flash to RAM.pdf

I'll go through the code and inform you accordingly.

Regards,

Gautam

0 Igor Gorbachev over 12 years ago

Guru 20525 points

Hi,

in addition to the above you can try to modify wait states execution and write accesses in the flash memory.

Regards,

Igor

0 Narasimha Prasad over 12 years ago in reply to Gautam Iyer

Prodigy 100 points

Thanks Gautam.

I will have a look at the application note you provided

0 Narasimha Prasad over 12 years ago in reply to Igor Gorbachev

Prodigy 100 points

Hello Igor,

Could you point me towards any documentation regarding that?

Thank you

0 Igor Gorbachev over 12 years ago in reply to Narasimha Prasad

Guru 20525 points

Narasimha,

you can refer to the following materials:

1) this AR (p.12-13) 2476.TI_Running_from_Flash_spra958l.pdf,

2) Data Manual of your DSP (SPRS439M, p.40, 183) 8103.TI_TMS320f28332-35_manual.pdf,

3) SPRUFB0D (p.22) 2425.TI_TMS320x2833x, 2823x System Control andsprufb0d.pdf.

Regards,

Igor

C2000™︎ microcontrollers

C2000 microcontrollers forum

Execution from flash very slow.