Re: [Discuss-gnuradio] Using the MIMO port for serial comm. to a Virtex5 board

[Matt Ettus]

On 11/24/2009 03:10 PM, Charles Irick wrote:
> Hello,
> I'm looking to use the MIMO port to send serial data to a Virtex5
> board and am trying to get an idea of how to set up the USRP2 to
> achieve this.
>
> - I was wondering how a simple loopback test might be achieved.
> Something simple like taking what the TI chip gives the FPGA and
> sending it back out. Not sure if I should be concerning myself with
> the HDL code running on the Spartan 3. (usrp2/fpga/serdes)


The easiest way to check for physical connectivity would be to turn on 
the loopback mode in the TI SERDES chip itself.  You can do this by 
changing some firmware in the aemb, without having to recompile the FPGA.

> - It looks like I will probably have to flash the firmware and I'm not
> sure what the best s/w configuration would be. (mimo_tx.bin,
> serdes_txrx.bin, my own,  ...)

Yes, you'll need to do firmware.  If you just modify the main() function 
to set the loopback, it doesn't matter which firmware you start with.

> My guess: I will need to create my own app.c in usrp2/firmware/apps
> which receives a serial packet and sends it back out, compile this,
> then flash it to the SD card to be run on the aeMB.

Once you have confirmed physical layer communications using the loopback 
test above, run the sd_gentest.bin firmware.  It will send packets out 
at a high rate and look for them to be sent back.

Let me know if you have any further questions.

BTW, I don't know how you intended to physically connect the boards. 
The best long term solution is to have your own custom board which 
implements the connections we use (SAS).  In the short term, you can buy 
a SAS to quad SATA breakout cable.  This would connect right to the SATA 
headers on many FPGA eval boards.

Matt