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ADSP21371 + ISSI 42S32800 SDRAM not working

Question asked by rk1980 on Mar 25, 2011
Latest reply on May 18, 2011 by DeepV

Hello,

 

I'm currently trying to get the ADSP21371 working with a 42S32800 SDRAM chip, but I don't have success yet. The board is our own design and it wa previously stuffed with the Micron MT48LC4M32 (same SDRAM like on the EZ-KIT). With the Micron SDRAM everything works fine.

For the MT48LC4M32 I used the following code for initialisation:

*pSDRRC= (0x7F7)|(SDMODIFY<<17)|SDROPT;

*pSDCTL= SDCL3|DSDCLK1|SDPSS|SDCAW8|SDRAW12|SDTRAS7|SDTRP3|SDTWR2|SDTRCD3;

It is take from Analog's talkthrough-exanple and does work.

Now I want to have more RAM. Therefore, I replaced the MT48LC4M32 by 42S32800 because they have the same pin layout and it looks like that they're fully compatible regarding timing.

What I understand from the datasheet is that the 42S32800 has a wider Bank Column Address Width of 9 bits while the MT48LC4M32 has only 8 bits.

Therefore, I changed the 2nd line to:

*pSDCTL= SDCL3|DSDCLK1|SDPSS|SDCAW9|SDRAW12|SDTRAS7|SDTRP3|SDTWR2|SDTRCD3;

But the doesn't work. What I'm I doing wrong? Any ideas?

 

Raphael

 

P.S. When I don't change SDCAW8 to SDCAW9 (still driving the SDRAM with 8 bits) I do get data from the SDRAM but they're disturbed.

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