CCS/TM4C123GH6PM: Dynamic memory allocation in flash

nihit bhavsar

Part Number: TM4C123GH6PM

Tool/software: Code Composer Studio

Hi,

TM4C123GH6PM has 256kB flash and 32kB SRAM, the reason i mentioned this is because i am working with large datasets which might not fit in RAM.

I know it can be done using "section" but the matrices are declared dynamically everywhere in the code, is there a way i can store the data in flash and access it in my code when required?

Thanks,

Nihit

over 7 years ago

0 Charles Tsai over 7 years ago

TI__Guru**** 191316 points

If the matrices change their values during runtime then you cannot store them in the flash. Your heap and stack needs to be in SRAM.

0 nihit bhavsar over 7 years ago in reply to Charles Tsai

Prodigy 175 points

The matrices will be read-only, can you please give an overview how to store those matrices in flash?

0 Charles Tsai over 7 years ago in reply to nihit bhavsar

TI__Guru**** 191316 points

Please refer to the #pragma SET_DATA_SECTION usage in the c compiler user's guide in www.ti.com/.../spnu151r.pdf.
Once you define the section name then you can then map the section to the RAM in the linker file.

0 cb1_mobile over 7 years ago in reply to nihit bhavsar

Guru 117855 points

Both "high & slowed demands" will be placed upon the MCU's Flash Memory - when deployed as you note.

Would not a device w/vastly more SRAM - or your current selection - but augmented w/"external" SRAM - far, "better meet" your requirements?

0 nihit bhavsar over 7 years ago in reply to cb1_mobile

Prodigy 175 points

I do not want to spend more resources by interfacing external SRAM rather i prefer using flash since my application is readonly, Charles i will look into the document and get back to you.
Thank you so much all, for the help.

0 cb1_mobile over 7 years ago in reply to nihit bhavsar

Guru 117855 points

If yours is a, "one time or (very) few times Flash load" AND if your application can tolerate the "considerable duration" - required by the rather complex, multi-part Flash Programming procedure - then I (may) agree.

Small - SPI, quad-bit accessed - Flash Memories exist - EXACTLY for such requirements - perhaps for (good) reason...

0 nihit bhavsar over 7 years ago in reply to Charles Tsai

Prodigy 175 points

This approach won't work, to change any flash value to 1 bit, it is required to erase 1kB and then program flash to set bits to zero. However, there's a limit on how many times a flash can be erased before it wears out. There's a section on flash programming in the TM4C123GH6PM datasheet on pg 531, realized that i should mention it here if anyone in the future needs help on same issue.

Best,
Nihit

0 cb1_mobile over 7 years ago in reply to nihit bhavsar

Guru 117855 points

nihit bhavsar said:
This approach won't work, to change any flash value to 1 bit, it is required to erase 1kB and then program flash to set bits to zero. However, there's a limit on how many times a flash can be erased before it wears out.

INDEED! Which is why - one here - suggested "Use of the superior, "Purpose-Built" external, Serial Flash - which proves highly advantaged (i.e. far FASTER, easier to use, & far more ROBUST!)

0 nihit bhavsar over 7 years ago in reply to cb1_mobile

Prodigy 175 points

The aim is to implement this high bandwidth algorithm on cheap standalone device.
Thanks for all for the help and support!

0 nihit bhavsar over 7 years ago in reply to nihit bhavsar

Prodigy 175 points

Edit : high bandwidth, high memory

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CCS/TM4C123GH6PM: Dynamic memory allocation in flash