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how about MMU?

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Posted by billy nguyen

on Jan 20 2011 10:28 AM

Hi guys,

I have a problem in my reserching, it is function of MMU-Memory Management Unit in microcontroller lm3s8962. And without MMU, what capacity will a microcontroller loose?

thanks in advance,

Billy.

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Posted by billy nguyen

on Jan 20 2011 10:29 AM

Intellectual290 points

Hi guys,

what function is MMU in a microcontroller?

thanks,

billy

Posted by Robb Sabolovic

on Jan 20 2011 11:11 AM

Intellectual1865 points

Hi Billy,

Would you please explain your question further? There is not an MMU (Memory Management Unit) inside the lm3s8962. There is a MPU (Memory Protection Unit), but it is not an MMU and it is not intended to support virtual memory.

If you only need to protect your system resources and tasks from unwanted access, then you can use the MPU, but if you need to support virtual memory, then the MPU cannot support this.

Please refer to section 3.1.4 Memory Protection Unit (MPU) in the lm3s8962 device datasheet.

Best Regards,

Robb

Posted by billy nguyen

on Jan 20 2011 22:35 PM

Intellectual290 points

Hi Robb,

I know that there is MPU in lm3s8962, but when I surfed web, i saw many definition of MMU, including protection memory, but i have not understood MMU yet, such as the action of MMU, the important of virtual address, if a microcontroller have no MMU or MPU, what will happen?

thanks,

Billy

Posted by Colombo Carlo

on Jan 21 2011 03:08 AM

Expert4915 points

Hi Robb ,

please you can find more detials on MPU in ARM intro to cortexm3 paper here : http://www.arm.com/pdfs/IntroToCortex-M3.pdf

about mmu , a nice start can be wikipedia : http://en.wikipedia.org/wiki/Memory_management_unit

best regards

Carlo