[avrdude-dev] [bug #26910] Terminal mode over USB/Dragon: dumping Flash is extremely slow

[Vincent Trouilliez]

URL:
  <http://savannah.nongnu.org/bugs/?26910>

                 Summary: Terminal mode over USB/Dragon: dumping Flash is
extremely slow
                 Project: AVR Downloader/UploaDEr
            Submitted by: troutrou
            Submitted on: Mon 29 Jun 2009 15:11:42 UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Vincent Trouilliez
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

I really love the terminal mode. I used to have a DIY parport cable, and
dumping Flash content was blazingly fast, I used it often. However I have now
purchased a Dragon to replace my DIY cable, and it appears that dumping a
single tiny litle KB of data takes... 60 seconds !  IOW, this feature has
become useless :-(

I enquired a lot on avr-chat, and it would seem that the problem is due to
avrdude reading Flash bytes one at a time, and that although this is fast over
parport, it's is extremely inefficient over USB, because of the very nature of
USB.

So I think this could be fixed simply by NOT reading bytes one by one, but
instead read a block of for example 2KB (which takes about one second, this is
fast enough), regardless of how many bytes the user asked for. So if, say, I
ask for 128 bytes, avrdude reads 2KB in one go, in order to retrieve data
quickly, then displays only the first 128 bytes (or whatever the user asked
for) on the screen.
This way the user gets to see the data very fast, no matter if he asked for
just a few bytes, or a few KB's.






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