[Discuss-gnuradio] USRP2 and MIMO

[Arun Pillai]

I have questions about using MIMO on USRP2, and also debugging FPGA code 
on USRP2. I am not using UHD.

1. Connecting 2 USRPs with the MIMO cable:

I am looking at the code for the mimo_tx firmware and do not see how
control packets, say, setting frequency, interpolation, gain etc. are
sent to the slave. The mimo_app_common_v2.c handle_control_chan_frame
function seems to drop these packets right after handling them. The
example code in usrp2/host/apps/test_mimo_tx.cc does not seem to do
anything special either to deal with this, in fact, the code to set any
board specific parameters is commented out. The mimo_tx_slave still has
the handle_control_chan frame code in app_common_v2.c which it uses (not
mimo_app_common). Does that mean the slave USRP also needs to be
connected via ethernet, and one needs to get a handle via the
usrp2::make interface separately to the master and slave to set control
parameters (although the example code in usrp2/host/apps/test_mimo_tx
does not do that)?

2. Debugging FPGA code on the USRP2:

The USRP2 fpga space available is so small that I can't really
effectively put chipscope on it. What debugging techniques or tools do
you use to debug the FPGA code on the USRP2?

Thanks,
Arun