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RM48 - EMIF MPU Configuration

Hector_Tortosa
Intellectual 475 points

Hi,

I have configured my external flash with the following configuration:

Thanks to this I could solve this other issue:

http://e2e.ti.com/support/microcontrollers/hercules/f/312/t/188446.aspx

The Ext Flash has been tested and works fine (timming is not adjusted still, so I have all the values at maximum)

My software downloads some code into the device, makes a crc and then executes that code. In the internal flash it worked well.

But when it jumps to the external flash, I can see in the dissasembly how goes from internal flash to external flash. However in the first instruction that executes in the external flash it goes to prefetch.

For me this sounds like a MPU configuration.

It's my Ext Flash region configured properly?

Thanks.

  • 0
    TI__Mastermind 49120 points

    Hi Hector,

    You need to configure external memory as device-type or strongly-ordered type for correct write operations. You have done so by configuring the MPU properly. In order for you to execute instructions from this memory, you need to now configure it as "normal" type. This is a requirement from the CPU and is stated in the Cortex-R4F TRM (on page 239 in revision r1p3) in the section titled "Region access permissions".

    Below paragraphs are pasted from the relevant section in that TRM:

    Instructions cannot be executed from regions with Device or Strongly-Ordered memory type attributes. The processor treats such regions as if they have XN permissions.

    Regards, Sunil