Thank you all. I will try some power supply cycling to see if I can
reproduce the problem.

Thank you all for your input.Will try a bit of power supply cycling may
reproduce the problem.

Arthur Richards wrote:
> We have an 87c51 system which uses a 93C06 EEPROM to hold configuration
> data. The units operate 7/24 and on average lost their data every few
> months. Sometimes ( if not always ) they erase to 0ffh's. I cannot find
> anything wrong with the micro code.
> 
> Has anyone experience hardware errors with these devices?

I recently heard of an inherent weakness of all EEPROMs at
low voltage. I'd have to look it up. The essence was to
have a fast transition from 0V to operating and back.
Especially  recommended was a shunt resistor over the power
supply to make the power off faster. Eg 1k @ 5V or so.

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Spehro Pefhany schrieb:

> >We have an 87c51 system which uses a 93C06 EEPROM to hold configuration
> >data. The units operate 7/24 and on average lost their data every few
> >months. Sometimes ( if not always ) they erase to 0ffh's. I cannot find
> >anything wrong with the micro code.
> 
> Usually something to do with the micro controlling them.. and
> electrical noise or improper startup and shutdown.

Especially power up might cause problems, if CS is not explicitly
held inactive (low) until VCC has reached the operating range.
If you are interfacing to the '51 directly (particularly CS),
this might be an issue.
There is a detailed AN on the website of STMicroelectronics about this.

-- 
Dipl.-Ing. Tilmann Reh
Autometer GmbH Siegen - Elektronik nach Ma�.
http://www.autometer.de

==================================================================
In a world without walls and fences, who needs Windows and Gates ?
(Sun Microsystems)

Hi,
Perhabs you write a lot into the EEPROM and the memory has reached its max
number of erasure / programming....

Yvan

**********************
            YBDesign
  http://www.ybdesign.fr
**********************

Tauno Voipio <tauno.voipio@iki.fi.NOSPAM.invalid> a &#4294967295;crit dans le message :
eEKOb.24$QR3.21@read3.inet.fi...
> Arthur Richards wrote:
> > We have an 87c51 system which uses a 93C06 EEPROM to hold configuration
> > data. The units operate 7/24 and on average lost their data every few
> > months. Sometimes ( if not always ) they erase to 0ffh's. I cannot find
> > anything wrong with the micro code.
> >
> > Has anyone experience hardware errors with these devices?
> >
>
> Watch out for brownouts (voltage dips) small enough to make
> the -51 misbehave but not low enough to activate the write
> protection of the EEPROM.
>
> We had a similar problem with a 8051 and EEPROM, and the
> problem was cured with a brownout detector / reset chip.
>
> It seems that the 8051 family chips start to misbehave
> and spew all kinds of rubbish on the bus lines just
> before dying on power starvation.
>
> HTH
>
> Tauno Voipio
> tauno voipio @ iki fi
>
>

Arthur Richards wrote:
> We have an 87c51 system which uses a 93C06 EEPROM to hold configuration
> data. The units operate 7/24 and on average lost their data every few
> months. Sometimes ( if not always ) they erase to 0ffh's. I cannot find
> anything wrong with the micro code.
> 
> Has anyone experience hardware errors with these devices?
> 

Watch out for brownouts (voltage dips) small enough to make
the -51 misbehave but not low enough to activate the write
protection of the EEPROM.

We had a similar problem with a 8051 and EEPROM, and the
problem was cured with a brownout detector / reset chip.

It seems that the 8051 family chips start to misbehave
and spew all kinds of rubbish on the bus lines just
before dying on power starvation.

HTH

Tauno Voipio
tauno voipio @ iki fi

On Mon, 19 Jan 2004 13:00:45 +1100, the renowned "Arthur Richards"
<fake@address.com.au> wrote:

>We have an 87c51 system which uses a 93C06 EEPROM to hold configuration
>data. The units operate 7/24 and on average lost their data every few
>months. Sometimes ( if not always ) they erase to 0ffh's. I cannot find
>anything wrong with the micro code.
>
>Has anyone experience hardware errors with these devices?

Usually something to do with the micro controlling them.. and
electrical noise or improper startup and shutdown. 

Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

We have an 87c51 system which uses a 93C06 EEPROM to hold configuration
data. The units operate 7/24 and on average lost their data every few
months. Sometimes ( if not always ) they erase to 0ffh's. I cannot find
anything wrong with the micro code.

Has anyone experience hardware errors with these devices?

Thanks,
Arthur