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The internal expanded RAM(XDATA) on AT89C51RB2 cannot be used

marc siah

Hello everybody, I am testing a program for AT89S54(AT89C51RB2) with uVision2.As you konwn,this chip has 768 bytes expanded RAM(XRAM).I want to use the XRAM for my program,but the XRAM space cannot be accessed. The site of AT89C51RB2:")
REGFILE=AT89C51RB2.H("Atmel")
SFILE="STARTUP.A51" ("Standard 8051 Startup Code")
SIM=S8051.DLL DP51.DLL("-pATRB2")
____________________________________________________

And in the option of my project,I have defined as below.
Selected__________________________________
_______Memory Model:[Large:varialble in XDATA]
Checked BOX______________________
_______Use On-chip XRAM(0x0-0x3FF)

What should I do for setting uVision2?

Thanks in advance.

Parents
  • 0 in reply to marc siah

    The array number :100 is decimal,not hex.
    my point exactly. how does an array nof 100d result in xdata=256.
    OH you are using the large model, I just can't visualize anyone doing that. That may explain the above.

    anyhow, to use a chips "internal external data" :) you usually have to set some bit in some SFR in the beginning of startup (check your chips datasheet). It is a common misconception that that is done automatically by the assembler/compiler/linker.

    Erik

Reply
  • 0 in reply to marc siah

    The array number :100 is decimal,not hex.
    my point exactly. how does an array nof 100d result in xdata=256.
    OH you are using the large model, I just can't visualize anyone doing that. That may explain the above.

    anyhow, to use a chips "internal external data" :) you usually have to set some bit in some SFR in the beginning of startup (check your chips datasheet). It is a common misconception that that is done automatically by the assembler/compiler/linker.

    Erik

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