[avrdude-dev] [bug #21954] verify fails for masked ('x') bits

[Emil]

URL:
  <http://savannah.nongnu.org/bugs/?21954>

                 Summary: verify fails for masked ('x') bits
                 Project: AVR Downloader/UploaDEr
            Submitted by: zelea2
            Submitted on: Saturday 01/05/2008 at 03:16
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Emil
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

AVR_CMDBIT_IGNORE is not used properly when reading bits.
The current workaround is using 'x' for both read and write
operations then the verify won't fail. This is however not 
following Atmel's documentation which says reserved bits should
be programmed to 1 because they might get used in the future.
The bit value for IGNORED bits is fixed to 0 so 'x' bits get
actually programmed to 0. A proper implementation would mask
the programmed and verified values before the comparisson.

Example:

$ avrdude -p m88p -c stk500v2 -P /dev/ttyS0 -u -U lock:w:0xff:m

avrdude: AVR device initialized and ready to accept instructions

avrdude: Device signature = 0x1e930f
avrdude: reading input file "0xff"
avrdude: writing lock (1 bytes):

Writing |                                                    | 0% 0.00s
***failed;

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0xff:
avrdude: load data lock data from input file 0xff:
avrdude: input file 0xff contains 1 bytes
avrdude: reading on-chip lock data:

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0xff != 0x3f
avrdude: verification error; content mismatch






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