Hi Sylvain.
On Fri, Jul 27, 2012 at 9:04 AM, Sylvain Munaut 246tnt@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