Raghunathan R wrote:
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If you need only a little bit of external memory of less than 256 bytes, then use the MOVX @Ri type instruction and P2 will then be available for normal use by your program. P2 is used by the MOVX @DPTR type instructions only.
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Sorry but not true.P2 output state is momemtarily affected by both MOVX instructions.If one used MOVX @DPTR then P2_pin=DPH.If one uses MOVX @R0/R1 then P2_pin=P2 latch.You may not decode P2 if RAM is less than 256 but making P2 act as general purpose i/o when any MOVX is in code
is not a good idea.
Pranav