[Discuss-gnuradio] Help using lfsr_32k with the USRP

[mjquinn]

I have a program where I want to transmit a lfsr_32k_source_s and check the
accuracy of the data that is received using check_lfsr_32k_s.  The program
works as expected if I connect the output of the transmitter directly to the
receiver in the software, i.e. fg.connect(tx_processing, tx_output) followed by
fg.connect(tx_output, rx_processing).  However, I have a problem if I try to use
the USRP to transmit and receive the data, i.e. fg.connect(tx_processing,
tx_output, usrp_tx) followed by (usrp_rx, rx_processing).  The program seems to
send and receive the data, but once the last packet is received, the program
locks up and does not display the results of the check_lfsr_32k_s function. 
Also, if you immediately try to re-run the program, the following error message
is displayed:
"failed interface 1
could not claim interface 1: Device or resource busy
usrp_basic_tx: can't open tx interface"

I was wondering if anyone had any ideas on where the mistake might be and how to
fix it?

Thank you,
Mike