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Altera_Forum's avatar
Altera_Forum
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13 years ago

uncontrolled SDRAM content change

Hi, I use a code which checks external SDRAM () by writing 0xAAAA and 0x5555 patterns. But the code always return an error code! When I check step by step SDRAM content with NIOSII IDE I can ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

With signal tap I can see that SDRAM controller is running. I plugged scope probes and I can see that data, address and control signals voltages change at every SDRAM access.

My code is already based on memtest from Altera. I did some change to let test run until end of SDRAM even a step with error.

Here is one test: 

for (pattern1 = 1, offset = 0; offset < nWords; pattern1++, offset++)
  {
    IOWR(baseAddress, offset, pattern1);
  }
for (pattern1 = 1, offset = 0; offset < nWords; pattern1++, offset++)
  {
    if (IORD(baseAddress, offset) != pattern1) {
      retCode = (baseAddress + offset);
      errCounter++;
    }
  }

The errCounter tell me that all steps get an error! I can't believe the entire SDRAM is down!