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.
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?
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.
Oopps! I looked at "24C16" and saw "27C16".
Thanks! Rich
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