Post by thread:[EE:] Ramtron FRAM

Hi, Interested to hear from anyone experienced with Ramtron Ferroelectric Nonvolatile RAM chips. I have a micro board that is experiencing occasional corruption of data stored in a FM24C256 FRAM chip. I wondering if these things are sensitive to electric/magnetic fields? I can not rule out errant code on the micro causing the corruption by errant writes to the FRAM, but also the level of EMI in this application is not insignificant which makes me curious. We have had problems with radiated EMI from this board design in the past, and that was overcome by metal coating the inside of the plastic enclosure. Any comments welcome. I'm curious enough to start some doing some bench tests to see if I can corrupt the contents of the FRAM. -- Brent Brown, Electronic Design Solutions 16 English Street, Hamilton, New Zealand Ph/fax: +64 7 849 0069 Mobile/txt: 025 334 069 eMail: spam_OUTbrent.brownTakeThisOuTclear.net.nz -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Good Q. Brent Brown wrote: > Hi, > > Interested to hear from anyone experienced with Ramtron Ferroelectric > Nonvolatile RAM chips. I have a micro board that is experiencing occasional > corruption of data stored in a FM24C256 FRAM chip. I wondering if these > things are sensitive to electric/magnetic fields? > I've designed them into lotsa stuff over the years, without the slightest failure. > I can not rule out errant code on the micro causing the corruption by errant > writes to the FRAM, but also the level of EMI in this application is not > insignificant which makes me curious. We have had problems with radiated > EMI from this board design in the past, and that was overcome by metal > coating the inside of the plastic enclosure. > Thats possible, of course. > Any comments welcome. I'm curious enough to start some doing some > bench tests to see if I can corrupt the contents of the FRAM. What I DO know is that it is NOT affected by a powerful alnico magnet. I've never understood exactly what is going on, but they certainly work. Let us know what you find out! {Quote hidden}> > -- > Brent Brown, Electronic Design Solutions > 16 English Street, Hamilton, New Zealand > Ph/fax: +64 7 849 0069 > Mobile/txt: 025 334 069 > eMail: .....brent.brownKILLspam@spam@clear.net.nz > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- Replier: Most attachments rejected -------------- Bob Axtell PIC Hardware & Firmware Dev http://beam.to/baxtell 1-520-219-2363 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

In message <40FF06CF.3030103KILLspamcotse.net> Bob Axtell <.....engineerKILLspam.....COTSE.NET> wrote: > I've designed them into lotsa stuff over the years, without the > slightest failure. I've used FRAMs too - never had a failure. Well, except for the time I fudged the write timing and ended up having the chip write randomness to its memory array, but that was entirely my fault :) > What I DO know is that it is NOT affected by a powerful alnico magnet. I've tried with a neodymium magnet from a hard disk actuator assembly. A good five minutes of waving the magnet in various directions - nothing. Well, except for the weird colour patterns on a nearby monitor. Oops. > I've never understood exactly what is going on, but they certainly work. Same here. The only differences between an FRAM and an E2PROM that really matter are the write timing (no 10mS write delay - yay!) and the fact that reads are destructive. Basically, the chip's onboard controller circuitry reads the contents of a given memory cell, then writes it back and sends the data it read back to the host device. They're nice chips - I think Ramtron are on to a winner here. I'm waiting until they start producing 256 and 512kbit FRAMs - they'd be perfect for sound recording and replay :) Later. -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, EraseMEphilpemspam_OUTTakeThisOuTdsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI ... 24 hours in a day, 24 beers in a case, Hmmm..... -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Belated reply...thanks to all who posted comments/ideas to my original query. That was only 2 weeks ago. Project is slipping into never-never land for a while due to lack of funding on my clients part. Shame. Hopefully though it will come back again and I'll be able to post the answer back here. They have found enough finances for the firmware to be overhauled (again, not by me), so there's a chance the problem may disappear when that is done. Best regards, Brent. -- Brent Brown, Electronic Design Solutions 16 English Street, Hamilton, New Zealand Ph/fax: +64 7 849 0069 Mobile/txt: 025 334 069 eMail: brent.brownspam_OUTclear.net.nz -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads