stlink swo usb capture tool

heh ;) it works :)

Dependencies
============
pyusb >= 1.x  (Tested with 1.0.0-0.4.a2.fc18)
(you have to work out udev rules yourself....)

Basic Usage
===========

python hack.py
connect
swo_file blahblahblah.log
swo_start stimulusbitmask
....
swo_start otherstimulusmask
...
exit (or ^d)


in another window:

# to see everything...
python swodecoder.py -f blahblahblah.log

# to see just stimulus port 2
python swodecoder.py -f blahblahblah.log -a 2


Tips
====
You _probably_ will want to edit swodecoder.py, in the PacketParser's
target parameter, if you want to change the output formatting.

http://false.ekta.is/2013/12/using-swoswv-streaming-data-with-stlink-under-linux-part-2/

Bugs
====
The STLink firmware gets into some screwy states sometimes, you need to
unplug/replug to get it back.  Boo :( (This is a bug in swopy's USB handling)

After streaming for a while, stably writing 40-60KB/sec, and seeing consistent
300-800bytes SWO data per frame, you'll see the STLink report that it has ~64KB
to dump, and then it gets a USB Transfer error and locks up.  Boo :(  As best I
can tell that's a firmware bug on the STLink, there's no field I can tell in
the USB responses to indicate there's any sort of overflow)

Sometimes the stimulus bits are weird.  Writing to bits that _should_ turn on
the channel you want doesn't.  Boo :( No idea what's going on there.