Re: [Discuss-gnuradio] USRP2 and MIMO

[Matt Ettus]

On 12/22/2010 02:21 PM, Arun Pillai wrote:
> 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)?


Those apps are old and should be deleted.  To see how the MIMO cable is 
handled you will need to get the packet_router branch from the UHD 
repository.

> 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?

I never use Chipscope, but I know people have used it on the USRP2 in 
the past.  I prefer to use the MICTOR logic analyzer connector, which 
gets you 34 pins.  If you need more than that you can use the GPIOs on 
the daughterboads if you put BasicRX and BasicTX boards on.  That gives 
you an extra 32 pins.

Matt