Re: [Discuss-gnuradio] USRP2 gigabit ethernet code

[Matt Ettus]

Jennifer Ann Petersen wrote:
>  Hi there,
>
>  I've been looking through the USRP2 gigabit ethernet code, and had a
>  few questions.
>
>  I noticed that the code for the USRP2 uses the open source gigabit
>  ethernet IP core from opencores.org <http://opencores.org> but that
>  it has an additional "Wishbone compliant core host interface"
>  (specifically I'm looking at MAC_top.v ) that isn't present in the
>  version available from opencores.org <http://opencores.org>. I'm not
>  terribly familiar with Wishbone, and I'm having some trouble
>  identifying its role in the USRP2 code I'm looking at - I saw that
>  it's supposed to be a standard interface between IP cores.  It looks
>  like the Wishbone inputs/outputs are tied to the internal signals for
>  the IP core - so is  it supposed to be some way of defining which
>  registers, etc on the  physical hardware get used for the registers,
>  etc in the core? If so, does that mean that anyone that uses that
>  core needs to use the Wishbone interface?


We use an almost completely rewritten version of the opencores tri-mode 
ethernet core.  The original simply does not work.

The Wishbone interface is for setting parameters in the core (like 
maximum packet size, speed, etc.), and for reading back performance 
monitoring counters.  The high-speed data does not go through the 
wishbone, it goes through the fifo interfaces.

Matt