Altera DE2: SDRAM Ctrler Vs. DDR SDRAM Ctrler

Altera_Forum · ‎08-22-2006

After 4 days struggling to make SDRAM work on the Altera DE2, i finally succeded.

I'm only able to do it using the SDRAM controller (not in megacore).

I first tried clocking the SDRAM with a -3ns delay but that didn't work (verify failed at download). Clocking the system with a 90MHz clk did the trick tho.

My question: is there any advantage of using the DDR SDRAM controller provided with megacore? I've tried using it, but I can't determine where to assign the dram_dqs[1..0] signals.

See the Altera DE2 pin table:

http://www.terasic.com.tw/attachment/archi...2_pin_table.pdf (http://www.terasic.com.tw/attachment/archive/30/de2_pin_table.pdf)

DRAM_DQS shines by its absence!?

-Pascal

Altera_Forum · ‎08-22-2006

Why would you want to use a DDR controller for an SDRAM? You use the controller that's appropriate for the memory on your board. This is, in your case, an SDRAM (single data rate) controller.

If your design doesn't work with a phase shift of -3.0ns, then this could be a problem with the Altera/Terasic provided examples. One that should be reported.

- slacker

Altera_Forum · ‎08-23-2006

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originally posted by slacker+aug 22 2006, 01:26 pm--><div class='quotetop'>quote (slacker @ aug 22 2006, 01:26 pm)</div>

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why would you want to use a ddr controller for an sdram? you use the controller that's appropriate for the memory on your board. this is, in your case, an sdram (single data rate) controller.[/b]

--- quote end ---

got point, i was confused weither it was sdram or ddr. i've my answer now.

<!--quotebegin-slacker@Aug 22 2006, 01:26 PM

if your design doesn't work with a phase shift of -3.0ns, then this could be a problem with the altera/terasic provided examples. one that should be reported.

--- Quote End ---

I will report if i've the time.

Thanks,

-Pascal

Altera_Forum · ‎08-23-2006

Microtronix has a SDRAM controller (http://www.microtronix.com/product_sdram.html), as well.