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Problem with DTPR

Astrid Wonner

Hello!

I'm using a CYGNAL C8051F020 with the CYGNAL C8051F uVISION2 DEBUG DRIVER v1.29, Keil C51 V7.05 with µVision2 V2.37.

I've got a problem which I've isolated like this:
The command 

MOVX @DTPR,A
writes the value of A both to the address specified by DTPR and to a address DTPR-0x1000, which in worst case contains any variable.
E.g. if DTPR = 0x12B9 the value in A is written to x:0x12B9 AND to x:0x02B9.
Can anyone help me? Thanks!

Astrid

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  • 0

    How do you have EMI0CF configured? Refer to the device datasheet. EMI0CF's post-reset value is 0b00000011, which configures the External Memory Interface for "internal only". This device has 4K (0x1000) of "internal" XRAM, so unless you've set EMI0CF to some other value, the byte at location 0x02B9 also appears at address 0x12B9, 0x22B9, 0x32B9, 0x42B9...

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  • 0

    How do you have EMI0CF configured? Refer to the device datasheet. EMI0CF's post-reset value is 0b00000011, which configures the External Memory Interface for "internal only". This device has 4K (0x1000) of "internal" XRAM, so unless you've set EMI0CF to some other value, the byte at location 0x02B9 also appears at address 0x12B9, 0x22B9, 0x32B9, 0x42B9...

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