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  1. RAM test question

    Hello!

    I have a board with NET+50 (with ARM7TDMI core) , NOR FLASH and SDRAM.
    And one question:
    Codes are stored in FLASH , if I want to test RAM and print out some
    message or get some command through RS-232 serial port before codes are
    loaded into RAM and begin to run.Then RAM test routine must be written
    in assembly language,right? Or can i write the test routine in C since
    assembly programming is very time consuming?

  2. Re: RAM test question

    Hello ,

    You can also write the RAM test routine in C!! It all depends on
    what kind of RAM test you want to perform before starting your
    application.

    Best Regards,
    Vivekanandan M

    > Zhenhuan Du wrote:
    > Hello!
    >
    > I have a board with NET+50 (with ARM7TDMI core) , NOR FLASH and SDRAM.
    > And one question:
    > Codes are stored in FLASH , if I want to test RAM and print out some
    > message or get some command through RS-232 serial port before codes are
    > loaded into RAM and begin to run.Then RAM test routine must be written
    > in assembly language,right? Or can i write the test routine in C since
    > assembly programming is very time consuming?



  3. Re: RAM test question

    I want to test RAM Address bus ,Data bus and Every Cell completely.
    Can you give me some hint? Thanks!

    Vivekanandan M wrote:
    > Hello ,
    >
    > You can also write the RAM test routine in C!! It all depends on
    > what kind of RAM test you want to perform before starting your
    > application.
    >
    > Best Regards,
    > Vivekanandan M
    >
    >> Zhenhuan Du wrote:
    >> Hello!
    >>
    >> I have a board with NET+50 (with ARM7TDMI core) , NOR FLASH and SDRAM.
    >> And one question:
    >> Codes are stored in FLASH , if I want to test RAM and print out some
    >> message or get some command through RS-232 serial port before codes are
    >> loaded into RAM and begin to run.Then RAM test routine must be written
    >> in assembly language,right? Or can i write the test routine in C since
    >> assembly programming is very time consuming?

    >


  4. Re: RAM test question

    "Zhenhuan Du" wrote in message
    news:ejsdhb$94v$1@news.cn99.com...
    >I want to test RAM Address bus ,Data bus and Every Cell completely.
    > Can you give me some hint? Thanks!
    >
    > Vivekanandan M wrote:
    > > Hello ,
    >>
    >> You can also write the RAM test routine in C!! It all depends on
    >> what kind of RAM test you want to perform before starting your
    >> application.
    >>
    >> Best Regards,
    >> Vivekanandan M
    >>
    >>> Zhenhuan Du wrote:
    >>> Hello!
    >>>
    >>> I have a board with NET+50 (with ARM7TDMI core) , NOR FLASH and SDRAM.
    >>> And one question:
    >>> Codes are stored in FLASH , if I want to test RAM and print out some
    >>> message or get some command through RS-232 serial port before codes are
    >>> loaded into RAM and begin to run.Then RAM test routine must be written
    >>> in assembly language,right? Or can i write the test routine in C since
    >>> assembly programming is very time consuming?


    If you can lock the 8K cache then you can use it for stack and local
    variables for a C app running directly from Flash. It is probably useful to
    find out how to do that anyway because you don't want the cache getting in
    the way of RAM testing.

    Peter



  5. Re: RAM test question

    Peter Dickerson wrote:
    > "Zhenhuan Du" wrote in message
    > news:ejsdhb$94v$1@news.cn99.com...
    >> I want to test RAM Address bus ,Data bus and Every Cell completely.
    >> Can you give me some hint? Thanks!
    >>
    >> Vivekanandan M wrote:
    >> > Hello ,
    >>> You can also write the RAM test routine in C!! It all depends on
    >>> what kind of RAM test you want to perform before starting your
    >>> application.
    >>>
    >>> Best Regards,
    >>> Vivekanandan M
    >>>
    >>>> Zhenhuan Du wrote:
    >>>> Hello!
    >>>>
    >>>> I have a board with NET+50 (with ARM7TDMI core) , NOR FLASH and SDRAM.
    >>>> And one question:
    >>>> Codes are stored in FLASH , if I want to test RAM and print out some
    >>>> message or get some command through RS-232 serial port before codes are
    >>>> loaded into RAM and begin to run.Then RAM test routine must be written
    >>>> in assembly language,right? Or can i write the test routine in C since
    >>>> assembly programming is very time consuming?

    >
    > If you can lock the 8K cache then you can use it for stack and local
    > variables for a C app running directly from Flash. It is probably useful to
    > find out how to do that anyway because you don't want the cache getting in
    > the way of RAM testing.
    >
    > Peter
    >
    >


    thanks for your advice ,Peter! It's really a good idea! Further
    question: What about an CPU without cache or integrated ram ?
    I think it's better finding a general solution.

  6. Re: RAM test question

    "Zhenhuan Du" wrote in message
    news:ek3vua$c1f$1@news.cn99.com...
    > Peter Dickerson wrote:
    >> "Zhenhuan Du" wrote in message
    >> news:ejsdhb$94v$1@news.cn99.com...
    >>> I want to test RAM Address bus ,Data bus and Every Cell completely.
    >>> Can you give me some hint? Thanks!
    >>>
    >>> Vivekanandan M wrote:
    >>> > Hello ,
    >>>> You can also write the RAM test routine in C!! It all depends on
    >>>> what kind of RAM test you want to perform before starting your
    >>>> application.
    >>>>
    >>>> Best Regards,
    >>>> Vivekanandan M
    >>>>
    >>>>> Zhenhuan Du wrote:
    >>>>> Hello!
    >>>>>
    >>>>> I have a board with NET+50 (with ARM7TDMI core) , NOR FLASH and
    >>>>> SDRAM.
    >>>>> And one question:
    >>>>> Codes are stored in FLASH , if I want to test RAM and print out some
    >>>>> message or get some command through RS-232 serial port before codes
    >>>>> are
    >>>>> loaded into RAM and begin to run.Then RAM test routine must be written
    >>>>> in assembly language,right? Or can i write the test routine in C since
    >>>>> assembly programming is very time consuming?

    >>
    >> If you can lock the 8K cache then you can use it for stack and local
    >> variables for a C app running directly from Flash. It is probably useful
    >> to find out how to do that anyway because you don't want the cache
    >> getting in the way of RAM testing.


    >>

    >
    > thanks for your advice ,Peter! It's really a good idea! Further question:
    > What about an CPU without cache or integrated ram ?
    > I think it's better finding a general solution.


    There is a point at which you have to trust something. Does your RAM and
    Flash share address or data busses? If so then a fault at the RAM might
    interfere with the Flash operation. How to you program the Flash in the
    first place - before soldering to the board or via JTAG. Its not uncommon to
    need some RAM to work for JTAG programming to work (e.g. download
    programming code into RAM). If you have RAM in your CPU and you trust the
    chip then I'd accept that as a gift. Writing code to test RAM *and* report
    failures without using any RAM for workspace is likely to be much harder
    work. To do this you will have to run from Flash and only use registers for
    work space. You won't be able to do it in C because you can't have a stack.
    With an ARM the subroutine call can be used without RAM but you'll need to
    avoid nested calls.

    Peter



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