[avrdude-dev] [patch #7437] modifications to Bus Pirate module

[Tim Vaughan]

URL:
  <http://savannah.nongnu.org/patch/?7437>

                 Summary: modifications to Bus Pirate module
                 Project: AVR Downloader/UploaDEr
            Submitted by: tgvaughan
            Submitted on: Sun 16 Jan 2011 04:25:02 AM GMT
                Category: None
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

Dear AVRDude dudes,

First off, thanks for writing such an awesome tool - if it weren't for you, I
wouldn't be able to tinker with AVRs.  (What a sad and miserable life that
would be! :-) )

In case you're interested, I've made a couple of changes/improvements I've
made to the support for dangerousprototypes.com's Bus Pirate.

The first change is structural.  During initialization, the previous
buspirate.c (specifically, buspirate_enable() ) sent a reset command to the BP
and parsed the resulting serial output to determine the versions of the BP
hardware and firmware.  This was then used to determine whether the binary SPI
mode could be used for communication with the MCU.  Unfortunately, this
approach has been a source of ongoing compatibility issues due to small
changes made to the BP user interface over the last few firmware revisions. 
Furthermore, the initial reset command will cause havoc with the next version
of the BP hardware (v4), as it will cause the USB connection to the BP to
disappear and reattach.

Following the suggestion of Ian Lesnet, the lead BP developer, I've therefore
removed the initial reset, as well as any attempt to detect the BP hardware or
firmware versions via the BP user interface. Instead, I've implemented a
try-then-fallback approach that attempts to enter the binary SPI mode, then
falls back to the original ascii mode in the event that this fails.  Entering
binary mode implicitly causes the BP to reset its internal mode settings,
which is why the explicit reset is unnecessary, but a reset is still performed
in the event that ascii mode is used. This change fixes all of the recent
compatibility issues as all but the earliest firmware versions support the
binary mode.   (The extended option "ascii" can still be used to force the use
of the legacy ascii SPI mode, if desired.  However, ascii mode is likely to
fail on BPs using recent firmware versions due again to small changes in the
ascii user interface.)

The second change is a feature addition.  Ian has added a new bulk SPI write
command to the latest BP firmware version.  The presence of this new command
is determined during initialization (again by trial and error, this time in
buspirate_start_spi_mode_bin() ) and, if found, a new buspirate_pagedwrite()
function is enabled which makes use of this command which speeds up writes to
AVR flash memory by about a factor of 4.  I've created an additional extended
option "nopagedwrite" which disables detection and use of this function in
case it's not wanted, and added an appropriate entry to the manpage
documenting this new option.

The attached patch includes these changes and is against the current svn
trunk.  If you're happy with the modifications, please let me know if there's
anything I can do to make them appropriate for inclusion in the avrdude code
base.  I've done my best to keep the changes/additions in line with the
existing style, but no-doubt there's plenty that could be done better.

Thanks again for all the hard work you guys have put in to opening up AVR
programming to *nix users!

Tim

p.s. I posted this to the list a few weeks ago, but didn't actually assign a
patch number - hence the double post.



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File Attachments:


-------------------------------------------------------
Date: Sun 16 Jan 2011 04:25:02 AM GMT  Name: avrdude_buspirate.patch  Size:
11kB   By: tgvaughan

<http://savannah.nongnu.org/patch/download.php?file_id=22418>

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