> -----Original Message-----
> From: piclist-bounces@MIT.EDU [mailto:piclist-bounces@MIT.EDU] On
Behalf
> Of IB Peter Feucht
> Sent: 20 February 2011 21:44
> To: 'Microcontroller discussion list - Public.'
> Subject: [PIC] Reliability of EEPROM content of 12F519
>=20
>=20
>=20
> Hi, all,
>=20
> I designed a small device about 2 years ago, which can be operated in
two
> different modes. Switching to mode 2 is only done here at the factory
by
> pressing a key in a specific pattern (Press 10 seconds, then wait
until
> light is off, then release key between 2 and 4 seconds, wait until
light
> is
> on again, then press 4 times within 3 seconds, someting like that).
The
> state of mode is stored in eeprom address 00, 0x00 for mode 1, 0x80
for
> mode
> 2.
>=20
> Now during the last 3 weeks about 10 customers called to tell, that
the
> device is suddenly operating in mode 2, even if it was shipped in mode
1.
> The procedure to change mode was never made available to the public
and
> futhermore there is no advantage at all for most customers to change
mode.
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> Question: Does anybody have information about the reliability of
eeprom
> content?
> How is it possible that eeprom content changes (electric field,
magnetic
> fields or or or)
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> Thanks for hlep.
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> Peter

Does this device regularly get power cycled?  Do you have brownout
protection enabled?

Regards

Mike

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