Re: [Discuss-gnuradio] help: cannot send after transport endpoint shutdown

[Eric Blossom]

On Wed, Jan 28, 2009 at 04:43:36PM +0800, Joreen Tan wrote:
>
> I'm trying it on the benchmark_tx and benchmark_rx scripts as i need
> to make it at least a half duplex communication between the two
> devices, i need to free up the resources if not i will get error
> message that states that the resource is busy.

It'll run half duplex automatically if you enable "auto_tr" mode...

...And benchmark_{rx,tx} are already set to do that.  
See line 73 in receive_path.py and line 99 in transmit_path.py (line
numbers are from the trunk.)

> Another question that i observed is that, there seems to be no way to
> stop the receiver once it is activated unlike the transmitter.

"Auto T/R" (Automatic Transmit/Receiver switching) handles it for you.
With Auto T/R enabled, the receiver runs unless there are samples in
the Transmit FIFO.  This is handled in the FGPA.

See the USRP FAQ and look at the inline docs in usrp_standard.h and
usrp_basic.h.  These two files implement the fundamental interface to
the USRP.  Almost all of that interface is available in Python.

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

Eric