I have boards that use eeprom NM24C16. Sometimes, after a time period, data written in factory is lost. Write pin (7) is connected to a micro. I think that noisy environement is the problem.
Someone know if exist a pin to pin eeprom less sensitive to noise? Or any other advice?
Thanks, Enzo
Find out why the micro is letting the write pin get asserted - maybe at turn-on or turn-off, or due to a programming problem. Maybe include some glue logic between the micro and the eeprom that requires a more complex and unlikely sequence before enabling write. Or, if it doesn't need to be written after it leaves the factory, use a jumper to disable it.
-- John
Have you covered up the quartz window? It might be getting erased; ambient light _does_ have an observable effect.
Good Luck! Rich
eeproms don't have quartz windows...
The OP should look carefully what happens during power up / power down / brownouts, for example does the processor run amok and scramble the settings? Or do the control pins go tristate and float to random values?
-- John Devereux
From which manufacturer is the device? The NM24C16 from Fairchild doesn't have a write pin:
And even if it would have such a pin, it is very unlikely that the microcontroller causes the problem, because for writing data you have to send valid I2C data to the chip.
Do you mean he NM24C17? This has a write protection pin. Maybe it could help to use this pin, if you read the chip and just the RW bit is changed in very noisy environments.
-- Frank Buss, fb@frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de
Oopps! I looked at "24C16" and saw "27C16".
Thanks! Rich
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