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SDRAM strange problem!

Question asked by behnamshakibafar on Oct 31, 2016
Latest reply on Nov 6, 2016 by A VT

Hi everybody


I designed new PCB with exact same schematic with my avaluation board, but got in trouble with SDRAM.

the K4S511632 chip is used. I tried a test code. what I can see is that error in writing or reading with a constant pattern. I write data on all space, then the on reading, every 4 32bit data I read, one time has error and every time error is same. I wrote 0xBBCCDDEE and I read 0x0xBBCCBBCC!


Can any one help me on this?

     /* Writing */     
     for (i=0; i<SDRAM_SIZE/4; i++)
       *char_wr_ptr++ = 0xEE;
       *char_wr_ptr++ = 0xDD;
       *char_wr_ptr++ = 0xCC;
       *char_wr_ptr++ = 0xBB;

       /* Verifying */     
     wr_ptr = (uint32_t *)SDRAM_BASE_ADDR;
       for ( i= 0; i < SDRAM_SIZE/4; i++ )
          if ( *wr_ptr != 0xBBCCDDEE )     /* be aware of endianess */
                 /* byte comparison failure */