RT117x: FlexRAM and OCRAM

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RT117x: FlexRAM and OCRAM

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mastupristi
Senior Contributor I

hi,
we talk about memory map and specifically OCRAM.

On RT1175 we keep the default configuration for FlexRam, consequently (confirm or warn me if I'm wrong) 256KB ITC + 256KB DTC. Since the memory array is 2MB, and we don't use ECC, I'd like to be able to access the remaining 1.5MB of OCRAM.
But let's take a closer look:

mastupristi_0-1716808726238.png

 

  • The various OCRAM memories make up a contiguous array of 2MB. The FlexRAM, where does it get its 512KB total TCM, from which of these listed?
  • We don't use the M4 core, though, we leave all the default settings, so I have no idea whether or not CM4 is powerdown. As long as I can access those 256KB I might think about keeping the core on but maybe clock gated, or some other mode?
  • What happens if I try to access the OCRAM locations actually used for TCM? Is it considered an alias of the TCM memories or gives a fault, or unpredictable behavior?

best regards

Max

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3 Replies

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Omar_Anguiano
NXP TechSupport
NXP TechSupport

The mentioned OCRAM M7 is the FlexRAM, the size may vary according to the ITCM and DTCM sizes.

M7 needs to be on un RUN mode, leaving it on default is okay.

I don’t understand your last question, if you access an area of OCRAM M7 configured as TCM it will behave as TCM since that area was previously configured as TCM. 

Solved: Re: Memory Map for i.MX RT1170 Processor - NXP Community

Best regards,
Omar

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mastupristi
Senior Contributor I

I don’t understand your last question, if you access an area of OCRAM M7 configured as TCM it will behave as TCM since that area was previously configured as TCM.

As I said I keep the default configuration for TCM (256KB ITC + 256KB DTC). I was wondering what happens if I access the locations between 0x20380000 and 0x203fffff.
I have tried some writes and verification. It turns out that most of the attempts I only have errors in verification, but occasionally I also have a BusFault.
Also I wonder if writing to the locations between 0x20380000 and 0x203fffff "dirties" the TCM locations, or simply the writes do not take place.

best regards

Max

 

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Omar_Anguiano
NXP TechSupport
NXP TechSupport

The result of using areas not in the flexram allocation is unpredictable and it is not suggested to do it.

Best regards,
Omar

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