Silly question Joe, Have you tried heating / cooling the card and changing the supply voltage to the limits? RP On 27 March 2015 at 08:34, IVP wrote: > > I just can't get over the fact that the computer can read the file > > intact after the problem happens. That means that the data itself > > is still in perfect condition on the card--there's simply no > > possible argument against that fact. > > I know. There's also the fact that when it's in "the condition" you > can cycle the power and it'll behave for up to several minutes > > > To me, it seems more likely that perhaps the card's behaviour - > > maybe the timing of some things - is changing in a way that is > > still within spec but perhaps violates a brittle assumption in your > > code somewhere. I can't see a card outright *failing* to deliver > > data simply because it's speaking SPI, when the data itself is OK. > > Maybe, but to me it seems improbable. > > Reading the card is a pretty simple affair and I can't imagine what > could drift, after such a long time and then for a subsequently shorter > time. Almost certain it's not the PIC because formatting the card > resets the problem without touching anything else. The PIC does > supply the timing via the SPI clock, which I think is about all the > influence I can have from the outside. > > I'm running a test now after some changes, and waiting for it to > break down so I can start gathering evidence. I'm not blinkered > to the PIC being at fault - had my share of time-wasting silicon > issues, including dodgy SPI flags on this very device - but it > does seem to be the bystander in this case > > Won't give up on it because this affects the viability of quite a few > projects. Maybe this card is symptomatic of a general problem > for large cards. As the pdf I posted a couple of days ago says, > as more and more billions of transistors are being put onto a > smaller and smaller piece of silicon the performance and reliability > is going to suffer > > Does the average consumer *really* need a 256GB card ? That's > an awful lot of lost selfies and mp3 > > Joe > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2015.0.5751 / Virus Database: 4315/9388 - Release Date: 03/26/15 > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .