I'm reasonably happy with the quality of the baseline data collected so far and I think I can now proceed towards actually trying some ideas to make the corruption go away for good.
I'll try next to add a 4.7 kOhm pull-up to FLASH_WE_N/WE# (write enable) and see if this has any effect on NOR corruption. If it doesn't, then I'll also add a pull-up to FLASH_CE_N/CE0 (chip enable). These pull-ups were discussed here: http://lists.milkymist.org/pipermail/devel-milkymist.org/2011-October/001902.html The statistical analysis so far allows us to estimate what amount of testing should be sufficient to encounter NOR corruption with a certain probability. Or in other words, we can calculate how many corruption-free cycles are needed to be able to claim with a certain confidence that NOR corruption has vanished: Test cycles Probability of not encountering NOR corruption (even though it is still there) 100 82% 1150 10% 2300 1% 3450 0.1% 10000 0.0000002% (This assumes exponential distribution, lambda = 1/500.) I'm still not sure whether there may also be some environmental parameter (e.g., temperature) that influences how often NOR corruption happens, if at all. Since controling and monitoring temperature would be harder than I had expected, I'll ignore this potential issue for now, and consider revisiting it later, when we have a likely fix. - Werner _______________________________________________ http://lists.milkymist.org/listinfo.cgi/devel-milkymist.org IRC: #milkymist@Freenode
