[avr-libc-dev] [bug #30085] memcpy_P on XMega does not clr NVM.CMD before copy

[Johannes Bauer]

URL:
  <http://savannah.nongnu.org/bugs/?30085>

                 Summary: memcpy_P on XMega does not clr NVM.CMD before copy
                 Project: AVR C Runtime Library
            Submitted by: joebauer
            Submitted on: Di 08 Jun 2010 15:45:48 GMT
                Category: Library
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: libc code
                  Status: None
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 1.6.7
           Fixed Release: None

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Details:

Hi there,

I've had some trouble today with the XMega. I used memcpy_P, which usually
worked just fine, except for a certain part of my code where it suddenly
produced garbled output. Tracing the source of the problem I noticed that on
the ATxmega I use the NVM.CMD register and set it to reading the calibration
row (0x02). However, since I did not return it to NOP (0x00), subsequent calls
to memcpy_P lead to a wrong result, since the behaviour of lpm has changed
with a changed NVM.CMD.

I suggest on the XMega to set NVM.CMD to zero in the beginning of memcpy or
include this in the docs, as it might cost someone else roughly a day in
debugging time :-/

Regards,
Johannes





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