[Sugar-devel] TA NXT plugin - cleanup and faster startup

[Martin Langhoff]

Hi Emiliano, Walter, list,

At http://dev.laptop.org/git/users/martin/turtleart/ you'll find
current TA master plus 2 patches. One is Emiliano's work, presented as
a single patch that only touches the relevant files. I think this is
good to merge.

Author: Emiliano Pastorino <epastorino at plan.ceibal.edu.uy>
Date:   Wed Mar 23 11:49:02 2011 -0400

    Add LEGO Mindstorms NXT2.0 plugin based on nxt_python 2.1.0

 icons/nxtoff.svg      |   84 ++++++++++++
 icons/nxton.svg       |   83 ++++++++++++
 plugins/nxt_plugin.py |  339 +++++++++++++++++++++++++++++++++++++++++++++++++
 po/es.po              |  168 ++++++++++++++++++++++++
 4 files changed, 674 insertions(+), 0 deletions(-)

The other one is

Author: Martin Langhoff <martin at laptop.org>
Date:   Wed Mar 23 12:33:08 2011 -0400

    nxt: delay finding the NXT brick, offer NXT block everytime

     - Startup delays --due to searching for NXT bricks -- are gone
       these delays affected all users with the libs installed.

     - All users that have nxt libraries installed see NXT blocks, and
       can load/edit files w them.

     - NXT detection is delayed until we hit an NXT-related action block

     - We only try to stop NXT motors if we have seen an nxt brick

 plugins/nxt_plugin.py |   52 ++++++++++++++++++++++++++++--------------------

To use/test my rework of Emiliano's patches, you'll want to have the
following rpms installed. They are built for Python 2.7 so F14 onwards
-- will prep F9 and F11 packages soon.
http://dev.laptop.org/~martin/public_rpms/nxt_python-2.1.0-1.fc16.noarch.rpm
http://dev.laptop.org/~martin/public_rpms/lego-udevrules-1.0-1.fc14.noarch.rpm

With Emiliano's patch there is a very visible delay on startup, due to
the attempts to find an NXT brick. In fact I got worried for a moment
that the plugins model was to blame. My patch waits until we actually
need to talk to the brick to search for it, and displays a nice error
msg if we can't find it.

One situation that is not handled well is unplugging/replugging of the
usb cable -- which may well happen between "runs" in a busy classroom.

We could address that by wrapping every call to the NXT libs with a
try/except that retries the _find_brick() and retries the command.

cheers,


m
-- 
 martin.langhoff at gmail.com
 martin at laptop.org -- Software Architect - OLPC
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 - don't get distracted with shiny stuff  - working code first
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