SDRAM problem on PPC405EP

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I have a design on PPC405EP processor.

In my design, a 2M * 32 bit SDRAM is used. But in practice, Only One typ
of SDRAM chip is supported, other Chip can not work in same configure.

I set the SDRAM config register as the following:
#define SDRAM_CFG    0x80800000
#define SDRAM_RTR    0x08200000    /* Define 133M refreshing rate.  133MHz
#define SDRAM_B0CR    0x00828001    /* 8M, Base=0x800000(8MB) */
#define SDRAM_B1CR    0x00028001    /* 8M, Base=0 , Mode 5 (11 * 8 * 4) */
#define SDRAM_TR     0x018FC01B    

EM638325 which made by ETRON Co. is supported, The other chip can no
work. Such as: K4S643232, W986432, 48LC2M32, VT3664324, and so on, the
all have -6 ns feature, working properly at 133Mhz on other system. I hav
check the data sheet of these chip, they are compatible and suitable fo
the actural configure.

But after many times trying, the other chips can not work properly.
The problem is like the following:
First write Data1 to Address1, and then write Data2 to Address2,
Third, Read from Address1 and Address2, the result is both Data2.

Because the EM638325 is difficult to purchase now, I need a replacer.
Please help me.

Thanks and Regards.

Rivor Wang


        
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Re: SDRAM problem on PPC405EP


Quoted text here. Click to load it

Failing all else, return to first principles. Capture the address,
clock and control signals on a storage scope. Compare to the datasheet
for the chip you are trying to use.


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