Addressing DDR-RAM

Hello, I've got a Xilinx Virtex 4 FPGA and would like to address the onboard DDR-SDRAM. I've found out that I can instantiate special DDR-IO flip flops by hand (and found an example in the ISE-Webpack documentation). But I'm still not sure how to address the DDR-SDRAM best, especially I don't know how to handle the DQS-Signal of the DDR-SDRAM, because I need a sensitivity on both edges.

Perhaps someone can even help me with a short example (VHDL preferred).

Thanks in advance,

Thomas

Reply to
Thomas
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Did you ever work with FPGA and DDR before ?

From your post I'd recommend just take an existing DDR controller and don't try to do one yourself. Even doing that is sometimes tricky ...

Sylvain

Reply to
Sylvain Munaut

I'd recommend searching the Xilinx APP notes for DRAM controllers; you might get good hits just by searching for "DQS." There's a bit of literature already there.

Reply to
John_H

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