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Placing a range of variables in external ram

Lars Bay Alexandersen

Hi
I have CortexM4 with external ram, since the external ram is slower than internally, I would like to have the possibility to place a variable in external ram. But I don't wan't to specify a exact adress of it.
Is there a attribute to set at the variable to place it in external ram ?
Lars

  • 0 

    int my_var __attribute__ ((__section__("SECTION_NAME")));

    I use the "--gnu" compiler flag. I'm not sure if the above works for non-gnu.

  • 0 in reply to Jonathan King

    Hi
    I have done that know, but I'm not sure that the compiler does what i wont it to.
    I have defined this:

    int my_var __attribute__ ((__section__("RAM1")));
    #define ExInt(x) int x __attribute__ ((__section__("RAM1")));
    ExInt(my_int);
    uint8 PowerLed __attribute__ ((__section__("RAM1"))) = Color_Green;

    I have set RAM1 to start at 0x60000000, when i open the map file i find that: Symbol Name Value Ov Type Size Object(Section) PowerLed 0x1fff04ec Data 1 nib.o(RAM1) my_var 0x1fff04f0 Data 4 nib.o(RAM1) my_int 0x1fff04f4 Data 4 nib.o(RAM1)
    I'm not sure that it is done the way i wish.

    Lars

  • 0 in reply to Lars Bay Alexandersen

    If you check/use the [Use Memory Layout from Target Dialog]

    Then you can use the [Options for file 'filename.c']

    Right Click the 'filename.c', choose the [Options for file 'filename.c'], you would see a dialog.

    Use that dialog.

  • 0 in reply to John Linq

    Hi That doesn't place the variables in external memory.
    My external memmory (RAM1) starts at 0x60000000, but variables are always placed into IRAM1 from 0x1FFF0000. What am i doing wrong ?

  • 0

    It seems something wrong with my desktop/Firefox/IE, sorry for any inconvenience caused.

  • 0 in reply to John Linq

    I checked my email box, only got two automated e-mail notifications from webmaster@keil.com.
    It is consistent with my successful posts.

    So, I think the scenario is:

    1. I used Firefox to post in this thread, but failed.
    2. Tried again, still failed.
    3. I used IE to post in this thread, but failed once again.
    4. Cleaned the history of my Firefox, tried to post, still failed.
    5. Cleaned all history of my Firefox, tried to post, it succeeded with a lot of unintended posts.