Picdude wrote: > 0x00 for example would be saved as '00000000', '01010101', and '11111111'. > > I can't say that Serial EE's are less prone to failure, but for the amount of data I was writing, I felt it would impart less writes to each cell, thereby not getting as close to the limits. Plus the extra space allowed me to do the RAID-type system much easier. > > Due to other timing constraints, I am not reading back to verify each byte group, but I'm writing to multiple groups, and with the data growing continuously, a scan of all groups on power up easily tells me which one was the latest. > There are actually two reasons to read immediately following a write: (1) an interrupt interfered with the write cycle; and (2) if you are writing at low voltage, say 2V, you might NOT have enough energy to run the charge pump at a proper level. > A microchip FAE/tech told me that what fails is the charge pump, but the info on this list indicates that the cells fail. Never saw any document indicating possible charge pump failure. > I look at the bottom line -- I've seen 5 failures (on 4 different instances of this circuit/product) with the system that stored data on the PIC's EEPROM, and no failures so far with the Serial-EE version (touch tree-trunks full of wood). > > My experience exactly. --Bob > Cheers, > -Neil. > > > > >> -------- Original Message -------- >> Subject: Re: [PIC] "Best of" PIC EEPROM Algorithm Clarified >> From: Peter Todd >> Date: Wed, April 26, 2006 7:09 pm >> To: "Microcontroller discussion list - Public." >> >> On Wed, Apr 26, 2006 at 01:47:39PM -0700, Picdude wrote: >> >>> Having been bitten by EEPROM failure on the PICs in the the past, I ended up using a serial EE and doing most of this, after discussion on and advice from this list. I also flipped bits in the copies of each byte so in case the EE all fails to a certain state, it won't be identified as valid data. >>> >> Flipped bits? Clever, and smart, I wouldn't have thought of that one. >> >> Do you think the stand-alone serial EEPROMs are less prone to failure? I >> mean, the few ones I've seen datasheets for, say the same reliability >> figures as PICs, but all the same... >> >> Be really nice if some MFG made an EEPROM with wear-leveling tech built >> into it for a cheap price... Of course, that's what flash memory is >> really. >> >> -- >> pete@petertodd.ca http://www.petertodd.ca >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist