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AT89C51ED2 startup code for large XRAM

Murray R. Van Luyn

Does anyone have an example of a startup.a51 file or any other method of initialising the XRAM to maximum 1792 byte size on an Atmel AT89C51ED2?

  • 0

    Don't the instructions (in the comments) in startup.a51 tell you everything you need to know?

  • 0 in reply to Andy Neil

    Hi Andy,

    Thanks for the reply.

    I can't work out the 1792 byte XRAM setup for the AT89C51XD2.

    I can't find anything other than a size in startup.a51. I think that should be 0x700.

    There's also 3 bits in an 'AUXR' register which must be set with the MSB high, but I'm not sure when these bits need to be set by, or really how to set them. Nothing I try seems to work!

  • 0 in reply to Murray R. Van Luyn

    There's also 3 bits in an 'AUXR' register which must be set with the MSB high, but I'm not sure when these bits need to be set by, or really how to set them.
    They need to be set at the very beginning of Startup (right after STARTUP1:) what bits to set the datasheet will tell you.

    Nothing I try seems to work!
    I guess you have been setting thr bits in the wrong place OR have not included/changed to your modified startup by its name in the assembly/link sequence by whatever method you use.

    Erik