I've built a custom AVR32UC3A0256 board based on the EVK110 development kit, but I use an 8MB ISSI SDRAM model instead of the 32MB Micron's model ( the model that comes with the EVK110 ) . ISSI's model is pincompatible with Micron's model. The only diference is that it uses one adress bit less.
I configured all AVR32 registers involved in the SDRAM access and I can read and write the entire memory, but my problem apears when I read sequentially a "big part" of the memory. I mean, if I exectue a large quantity of sequential reads over the memory I start to loose data, but if I insert some SDRAM write instuctions while I'am reading the SDRAM I don't lose any data. It seems like the SDRAM does not refresh properly while is being sequentially read , and the problem disapears if I force some write instruction while I'm reading.
// fill a part of the SDRAM
for (i = 0; i <260000;i++){
sdram[i]=(unsigned long)(i%255);
}
float_aux=long_aux;
// check written values
for (i = 0; i <260000;i++){
/* If I uncoment this part of the code, it works
if ((i%2048)==0){
sdram[i]=i%255;
}*/
if (sdram[i]!=(unsigned long)(i%255)){
num_errors++;
}else{
num_ok++;
}//if
}//for
It seems like the SDRAM doesn't refresh properly while is being sequentially read unless I place some write instructions in the middle. Probably I'am not configuring properly any of the registers.
Any idea?
Thanks
