I have a custom board with an altera EP1C12, a flash memory and a MT48LC4M32B2 SDRAM memory. Timings I set in SOPC builder are the default timings for this part.
When I set the value 0x00000000 to a particular location (it doesn't matter which location I choose), if I read back the same location after
5 ms (milliseconds!) I find 0x00000000; after 10ms some of the bits go to value 1; incrementally all the bits go to 1, and if I read it after 15ms, I read 0xffffffff.I tried increasing the refresh frequency (from 15.625us to 3us) with no success.
here is the test code, run from on-chip memory:
#include #include #include "system.h"
int main() { long i,j,k; long test,last; long values[32]; long times[32];
for(i=0;i