[Discuss-gnuradio] XCVR2450: Switch between sending/receiving mode

[Matthias Schäfer]

 Hi List,
I'm using the latest uhd fpga code and my own f/w on a USRP2 with the
XCVR2450 (REV 692) dboard.

After the tuning is done by the host, sending from f/w is no problem.
Also receiving works fine after setting
            sr_rx_ctrl->cmd = (0xE0000000 | BP_NLINES);
            sr_rx_ctrl->time_secs = 0;
            sr_rx_ctrl->time_ticks = 0;

My intention now is to detect a signal by observing the dsp samples on
the fpga (works, if the sr_rx_ctrl things are set like mentioned above)
and then send an interrupt to the f/w (works also) which then responds
by sending a short signal back. But after sending data to the
DSP-TX-buffer the usrp2 stops receiving. Just resetting the sr_rx_ctrl
fields with the values from above doesn't work anymore.

So my problem is the switching between sending and receiving modes. How
do I switch back to "receiving" mode after sending the data? Is it
possible to do this automatically with the ATR controller? If yes, how
do I have to setup the ATR registers? The values are handled outside the
fpga (if I understood that right) and so I don't know the meaning of
these values.

Thanks in advance.

Cheers,
Matthias