XILINX Artix-7 DDR2-RAM-Controller

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I had some experience with Virtex-4 and V5 DDR2 Controllers some time ago.

The underlying logic was generated in VHDL, but the Micron DDR2 models were only available in Verilog.

Fortunately, we had some mixed-language licences.

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I'm currently doing a DDR3-design for Artix-7. The controller code itself is also always provided as Verilog, only the top level is VHDL. Besides, when using Vivado, the entire process of generating an example design is broken when you select VHDL for generation.

To me it seems like the guy(s) doing the controller design is/are working with Verilog only. Kind of makes sense not to develop versions in two languages in parallel, but it used to be different... I did a DDR2-design on Virtex-4 with an older release of MIG (I believe it was 1.2 or so), and they provided VHDL-code for everything back then (which was good since it needed to be modified quite heavily).

The only thign you could do is uses Xilinx' simulation tool, that comes with mixed-language support by default.

Greetings, Sean

VHDL for everything? Even the memory models? I haven't seen any DDR2 memory models in VHDL. That would make you need a mixed language simulator license even if the full controller model was in VHDL.

Yes, I believe that most DDRx memory controllers (and other hard-ip) are written in encrypted (System)Verilog which a VHDL user could use using the SecureIP (Modelsim and Aldec?) license feature. I suspect that with their own "dual language out of the box ISIM simulator" Xilinx might have forgotten the other simulator users.

Even the memory models?

Yes, VHDL DDRx memory models are available from Hynix and RASSP. Unfortunately AFAIK most companies tend to use Micron which are all in Verilog. A friend of mine who works for a big avionics company asked Micron to provide some VHDL models but they never came back to him (no surprise I guess). It is not that expensive for a company the size of Micron to provide models in all 3 RTL languages. So perhaps now is a good time to promote Hynix memory models, they are twice as succulent...

I haven't seen any

That would make you need a mixed

Or complain to your simulator vendor that in 2013 simulators should be dual language out of the box for exactly this reason. All synthesis tools are now dual language so why not simulators.

Hans

Back then I used Samsung chips, and they provided precompiled (ModelSim) models for one of their DRAM chips (luckily, the one I was using, or one close enough). They even recompiled for me since I was using a newer ModelSim release than the one they had models for and the "refresh" option didn't work.

But that was the one and only time I had Samsung do anything good for me. They proved uncooperative in absolutely every aspect before and after that, so I've banned everything Samsung from all my designs for the past 10 years (and convinced most of my colleagues to do the same). Another one of those companies that just don't care if you buy less than a million units a year...

For my current design, I fortunately have a dual-language simulator license, so that's not an issue.

Greetings, Sean