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tombsj

Nexys Video (Artix 7) Ethernet MAC License

Question

I setup my Nexys Video for the first time, and tried to setup an echo server using Vivado/SDK. I followed the following tutorial: 

https://reference.digilentinc.com/learn/programmable-logic/tutorials/nexys-video-getting-started-with-microblaze-servers/start

When I go to generate a bitstream, I get the following error: 

[Common 17-69] Command Failed: This design contains one or more cells for which bitstream generation is not permitted:

design_1_i/axi_ethernet_0_U0_mac_U0/tri_mode_ethernet_mac_i/bd_929b_mac_0_tri_mode_ethernet_mac_v9_0_12)

If a new IP Core license was added, in order for the new license to be picked up, the current netlist needs to be updated by resetting and re-generating the IP output products before bitstream generation. 

 

The Nexys Video kit did not ship with a special Vivado license, am I required to purchase a license in order to use the Ethernet interface of my board?

 

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2 hours ago, tombsj said:

The Nexys Video kit did not ship with a special Vivado license, am I required to purchase a license in order to use the Ethernet interface of my board?

Ah, the old "I thought that what I was buying would let me do..." problem.

No, you can often get "evaluation" licences for some Xilinx IP if you sign up as a customer. Evaluation licenses range from letting you build a configuration file for a limited time to being almost useless. Intel has evaluation licenses that let you build a time limited (perhaps an hour) configuration file as long as the hardware is connected to Quartus. After the hour your board will no longer function until you re-configure it.  I doubt that you are wondering about this but no, evaluation licenses are not a good way to develop projects. Of course the purpose of evaluation licenses is to allow you to "try before you buy"; which is better than spending money hoping that the IP will solve problems that you can't. It's a bit dishonest for board vendors to suggest that you don't need to buy licenses in order to use one of the board interfaces when for all practical purposes you do. Even if you are capable of creating you own IP potential cupstomer should be aware of what it is that they are getting. As with all purchases the only operating legal principal would seem to be "buyer beware". (I'm not a lawyer nor do I provide legal advice")

None of the FPGA vendors that I know want to give customers robust full-bore Ethernet connectivity. If they provide source for the MAC it is encrypted and unusable. The truth is that Ethernet connectivity sells Microblaze and Nios. While these IP are "free" they use up considerable amounts of an FPGAs resources. Using vendor IP encourages customers to buy larger and higher priced silicon.... and on and on.

For most application using Ethernet a small subset of functionality is actually required. Ethernet is in many way in its own special arena. You can do battle with lions and tigers on the terms of the Caesar or figure out a better way. It's an investment in yourself but you can probably figure out how to use the Ethernet PHY well enough for most purposes by developing your own IP. Of course you need to be competent in developing FPGA logic with an HDL; but I suggest that this is always a requirement.

It would be nice if FPGA board vendors supplied HDL code to at least see all of the interfaces on a board function in some way. Unfortunately, I don't know of many who agree. At least a bit of honesty in advertisement would be considerate. Don't wait for that to happen either.

Edited by zygot

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@tombsj,

There are open source processors and network stacks you can use if you would like.  I currently maintain a build for my Nexys Video board that has a GbE controller, and I have another project with a bare working implementation of the IP stack--up to UDP only.  There's also a liteeth project that you might find useful for communicating with the PHY, as well as an open source lwip project for handling the protocol stack.  You might find these valuable.

As for Xilinx's IP, someone tweeted a response to me today pointing out that "Competition works, alternatives are growing steadily (slowly) but happening."

Dan

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@D@n

I can't argue one way or another with your offerings though I believe that anyone using them still needs to have some level of understanding about how Ethernet works. Once you figure out the PHY-FPGA interface it's mostly a case of constructing and parsing packets which isn't all that hard to do. Try slogging through the vendor script generated HDL that is in plain text; it usually provides insights to the newbie such as clock switching for 10/100/1000 speed selection. This part is usually available for study. I've never had a reason to do anything but 1G so far. I also embrace the idea of limited capability and controlled environment for my Ethernet applications.

There's also the ZYNQ route if you don't want to worry about hardware design.

Which brings me to the soap box. Apologies to the offended.

I believe that I've read that there are something in the order of 100 billion networked devices around the world. Even large companies, including router manufacturers, add to that number with consumer and commercial products having poor or no security. The internet is an analog of the old Wild West; only now the bad guys are criminal organizations and state agencies with almost unlimited budgets. It's bad enough that the companies that have figured out how to print money from internet activity, and with more cash on hand than most countries, aren't interested in making it a safe place to be connected to. More unsecured devices won't help the situation. I'm still on the side of being intelligently informed if you are going to make a board that can potentially become a platform for misuse. Learn stuff. Perhaps you might be a more responsible consumer as a side benefit.

 

Edited by zygot

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Hello,

Unfortunately yes, to use the Digilent made demo, you would need the license or the free trial of the TEMAC IP from Xilinx; this is stated both in the reference manual and the tutorial for the Microblaze servers. We do not currently have an alternate demo that gets around this limitation.

Thank you,
JColvin

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