I'm using a micro controller with ONFi peripheral to control multi-cell (2) NAND. I write the NAND (Micron) from the beginning to the end. I skip bad blocks and use a simple verification system:1) Write the page, including ECC codes 2) Reading it back and recalculating the ECCs
If ECC fails I write the same data to the next page.
However I seem to experience the following issue with *some* pages:
- During the verification the ECC consistently fails.
- Later, during read-out the same page seems to produce no errors
I keep to all the timing specifications (even far below). The issue does not seem related to the ONFi bus speed. Even at very slow speeds the same issue pops up. I've set the speed to 5 (fastest) and tried various drive strengths. None seem to matter.
a) Could this be related to some analog problem on the NAND it self? b) Has anyone else ever experienced these kind of issues? c) Could it be related to multi-cell? Since it shares bits with another page?
Thanks for any pointers! Vincent van Beveren