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Perhaps there are misunderstanding between us.
I want to implement a DDR2 controller to support DDR2 memory produced by different manufacturer or in different model.
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Ok, that is clearer.
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The other case is that DDR3 controller should be implemented on other board to support all kinds of model in stock.
It can be said that on the DDR2 board the controller only support DDR2. DDR3 board support DDR3 only too.
So I think DDR2 memory should have the same voltage and termination specifications, it can be implemented as north bridge chip does.
The most difficult thing is about the static timing parameter.
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The DDR2 and DDR3 controllers have timing parameters that can be configured. The main task for you as the designer is to perform a timing analysis to confirm that the timing requirements can be met.
If you look at the DDR speeds on Altera's web site
http://www.altera.com/technology/memory/mem-index.jsp and then compare the bus speeds to those on the DDR2/DDR3 data sheets, you will find that the controllers are quite slow, i.e., its not too hard to meet timing.
Cheers,
Dave
Honored Contributor
