Re: [Discuss-gnuradio] UHD Error handling from GNU Radio/Python

[Josh Blum]

On 07/19/2012 09:42 PM, Nowlan, Sean wrote:
> Hi all,
> 
> I am interested in being able to recover from UHD Error conditions
> such as not finding a USRP on startup or an Ethernet cable getting
> knocked loose (USRP N200). I implemented an uhd_async_message source
> but all I can do with that is read error codes corresponding to
> sequence errors, late packets, underruns, etc. It's nice to have the
> ability to take action based on these messages, but if an Ethernet
> cable gets knocked loose, nothing gets sent to the message queue (at
> least, not that I could find). Instead, UHD prints to stdout using
> some other thread and then my script hangs.
> 
> I hacked UHD's error printing code to do an exit after it prints
> whatever error occurred, and then a bash script handles restarting
> the Python program that's controlling GNU Radio behavior. I'm aware
> that there is a way to register a message handler function with UHD
> so that it won't just print to the screen and hang. Is there any way
> to implement this handler in Python and register the function with
> UHD? I don't normally post to both lists to avoid redundant spamming,
> but I'll take a leap of faith here. :)
> 

I think I see your point. There really isnt a good way to know that some
internal thread died. Whether it be in UHD or a gnuradio worker thread.

It might be a decent idea to queue up an async message into the queue
when an internal thread dies. Not sure how you might get the info from a
gnuradio scheduler thread though.

In the short term, if you do try to communicate with the device object
in someway that involves an over-the-bus communication, and the
transport is down, you will get a nice exception thrown all the way into
python which you can catch and react to.

Example, periodically set_time_source(..) which is harmless to do, but
causes bus traffic.

-josh

> Thanks, Sean Nowlan
> 
> P.S. - I'll sneak this question in with the technical one above: is
> the GNU Radio conference free to attend? Is there any registration
> required? Didn't see any such thing on the site, so I'm assuming it's
> free and the public can just show up and enjoy some awesomeness.
> 
> 
> 
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