No communication: MicroBlaze with AXI Ethernet Subsystem with DMA on Nexys4 DDR

[bklopp]

I am trying to get basic ethernet communication working with the AXI Ethernet Subsystem and DMA in a MicroBlaze design using a Nexys4 DDR board, I generated this design and get the following critical warnings:

I think the 12-1790 warning can be disregarded because my evaluation license is still current:

https://store.digilentinc.com/nexys-4-ddr-artix-7-fpga-trainer-board-recommended-for-ece-curriculum/

I'm not sure what is causing the other critical warnings. I have the implementation and synthesis logs attached to this post.

I created a Peripheral Tests project in SDK

and hangs at the "Running AxiEthernetSgDmaIntrExample() for axi_ethernet_0..." line:

More specifically, when I step through the program, it hangs at line 606 of xaxiethernet_example_intr_sgdma.c

I also created a lwip Echo Server example project:

But cannot connect when using Terra Term, I get a "connection refused" message on the PC side.

I also noted that the LINK/ACT and 100/10 leds do not light up on the Nexys4 DDR board while running either the peripheral or lwip SDK projects, which tells me it's definitely a hardware problem since those leds lit up on a previous hardware design using the AXI Ethernetlite on the same board. 

Thanks in advance.

[savula]

Hi @bklopp,

Please check this 

https://github.com/andrewandrepowell/mic_gather_data

Best Regards,
Srikanth
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[bklopp · Accepted solution]

I figured out the problem. The AXI Ethernet Subsystem is not compatible with the Nexys 4 DDR, since the PHY on that board is not a gigabit PHY, so it requires a RMII interface, while the AXI Ethernet Subsystem can only support RGMII or GMII.

I purchased a nexys video board, which has a gigabit PHY that supports RGMII and is therefore compatible with the AXI Ethernet subsystem.

[mr.ex]

You are fundamentally wrong. AXI Ethernet Subsystem is support MMI which can be connected to RMII for the LAN8720 via the "mii_to_rmii" ip core.