Reconfiguring flow graph

GNU Radio
1

I want to implement MIMO using gnuradio.
I already could do differential and coherent(BPSK) communication link
between two USRPs( daughter board Flex 2400 ).
right now for channel estimation in MIMO I need to do reconfigure flow
graph. As mentioned in
www.gnuradio.org/trac/wiki/Tutorials/WritePythonApplications
after fg.stop() I call fg.wait() and then reconfigure flow graph, as
bellow
…
fg.stop()
fg.wait() #reconfigure flow graph
print “hello”
fg.disconnect(fg.amp, fg.u)
self.subdev[0].set_enable(False)
self.subdev[1].set_enable(True)
fg.connect(fg.amp, fg.u)
fg.start()
…
but code waits in gt.wait() and never goes ahead(never prints “hello”).
what shall I do to fix it?
thanks,
Mehdi

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2

On Sat, Aug 16, 2008 at 06:25:10AM -0700, mehdimolu wrote:

  fg.wait()               #reconfigure flow graph

Mehdi
First off, please upgrade to the lastest stable or svn trunk code.

http://gnuradio.org/trac/wiki/Download

Then modify your code to use gr.top_block instead of gr.flow_graph.
Finally surround your connects and disconnects with
top_block.lock()/unlock(). Do not use stop()/start() to perform the
reconfiguration, use lock()/unlock().

See gr-utils/src/python/usrp_siggen.py for an example of correct usage.
Look at the _configure_graph method.

Eric

3

Hello,
thanks to Eric for his efforts in the forum.
I did the modifications recommended. but still problem is not solved.
I used lock()/unlock instead stop()/start() but still unlock doesn’t
work, I
mean in the code below

                  ...
  tb.lock()
  print "Locked to Reconfigure"
  tb.disconnect(tb.amp, tb.u)
  tb.subdev[0].set_enable(False)             # disable Antenna 1
  tb.subdev[1].set_enable(True)              # enable Antenna 2
  tb.connect(tb.amp, tb.u)
  print "Reconfigured"
  tb.unlock()
  print "Start Again"
                    ...

but still it doesn’t print “Start Again” .
I already in another example was able to reconfigure chain and run it
again
but in this code I couldn’t understand why it doesn’t work.
this flow graph contains stream_to_streams and streams_to_stream
blocks(which I have not used them in aforementioned example).
I am not really sure the problem is due to these blocks or …
every help is appreciated.
Mehdi

Eric B. wrote:

bellow
but code waits in gt.wait() and never goes ahead(never prints “hello”).
top_block.lock()/unlock(). Do not use stop()/start() to perform the
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