Plan for 10/100 Ethernet support for umTRX

Andrew Karpenkov plddesigner at gmail.com
Fri Jul 27 19:20:39 UTC 2012


Hi All!

May be it's easy just modify Ettus code for support Tri-Mode Ethernet. I
think that it is not so difficult.
In that way we can chose Ethernet PHY  work mode from host.
Also 'wait' feature (PAUSE frames / flow control)  available not only for
Gigabit Ethernet. Some 10/100 Ethernet Controllers support it (for example,
LAN9218).

Regards,
Andrew Karpenkov


2012/7/27 Robin Coxe <coxe at close-haul.com>

> Hi Sylvain.
>
> On Fri, Jul 27, 2012 at 9:04 AM, Sylvain Munaut <246tnt at gmail.com> wrote:
> > Hi,
> >
> >> The Ettus UHD framework adopted for the umTRX only supports GigE
> >> (simple_gemac).   A reworked, Wishbone-compliant 10/100 Ethernet MAC
> >> is included in the OpenRISC SoC project on Opencores.  It has been
> >> ported to the Digilent Atlys board, which has a Spartan-6 FPGA.
> >>
> >> http://www.chokladfabriken.org/projects/orpsoc-atlys
> >>
> >> I'll begin the port of this Ethernet MAC (a cleaned-up version of the
> >> 10/100 core on OpenCores) to the UmTRX and test it on Close-Haul's
> >> SP-605 Spartan-6 eval. board.   I'm not quite sure how long this task
> >> will take, but this feature falls into the
> >> "nice-to-have-but-not-urgent" category.
> >
> > But would it be 10/100/1000 ? or just 10/100 ?
>
> Just 10/100.   User would choose GigE or 10/100 via an IFDEF in the
> Verilog.    I suppose it would also be possible to multiplex in the
> simple_gemac with this 10/100 core and set the mode from the ZPU via
> the Wishbone interface.  There is a tri-mode Ethernet MAC that Ettus
> used to use on the USRP2, but I've never been able to make much sense
> of it.   If you have suggestions for a better way to add 10/100
> support, I'm definitely interested in hearing them.
>
> > Also, doesn't UHD make use of the 'wait' feature of Gigabit (i.e.
> > PAUSE frames / flow control ) to avoid loosing data ? This doesn't
> > exist on 10/100 IIRC.
> >
>
> I'm not all that familiar with UHD, so you probably know better than I
> do.  Perhaps Thomas could comment?
>
> -Robin
>
> --
> Robin Coxe  |  Close-Haul Communications, Inc.  |  Boston, MA
> +1-617-470-8825
>
>
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