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Dallas 80c400 access above 0x800000

Jan Zwiegers

I have hardware that needs to be accessed from 0xc00000 to 0xefffff. I have tried declaring it in an external ASM file and then to use it as a extern var in C. But this does not seem to work.

Please help!

asm file:

PUBLIC PPI_REG
PPI_REG XDATA 0x00c00000
END

c file:

extern unsigned char PPI_REG[4];
...
PPI[0] = 0x00;
...

Parents
  • 0 in reply to David Rose

    Hi David

    Thanks for the comments.

    The assembler type of access was given my Keil themselves. (I think) This is a workaround exactly for this kind of problem and specifically the DALLAS 80C400.

    In the end I will most likely have to settle for the assembler solution, it's just that the C code is alread complicated as is, but I should be able to separate certain parts and only leave the actual hardware access to assembler.

    Thanks again.

Reply
  • 0 in reply to David Rose

    Hi David

    Thanks for the comments.

    The assembler type of access was given my Keil themselves. (I think) This is a workaround exactly for this kind of problem and specifically the DALLAS 80C400.

    In the end I will most likely have to settle for the assembler solution, it's just that the C code is alread complicated as is, but I should be able to separate certain parts and only leave the actual hardware access to assembler.

    Thanks again.

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