AVR-Chat

Hello Gary,

Well ... an interesting problem ... my opinions follow ...

If it was me the first thing would be to find the source of the EEPROM write
errors in the similar application.

Check the read/write code ... check the grounds ... the bypassing ... the
filtering ... etc. Find the problem.

Leave no stone unturned so to speak.

All else before finding the problem is by your own words presumption.

Find the problem first then evaluation fixes if necessary.

Jim



----- Original Message ----- 
From: "Gary J. Melvin" <n9auw@garmeltech.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Thursday, April 06, 2006 8:39 AM
Subject: [AVR-Chat] EEPROM writing with elec. noise


> Hello,
>
> "Long time listener, first time caller."
>
> I've taken on an ATmega16-based project.  One of the requirements is
> that I need to write up to 3 bytes of data to EEPROM in a potentially
> electrically noisy environment.  I've never used its EEPROM before, but
> it looks relatively uncomplicated.
>
> My client has another product in a similar application which has been
> causing them a lot of grief with random EEPROM write errors, presumably
> due to noise glitches.  (They use the built-in Brown Out feature  -
> both trigger settings produced the same results.)  Obviously, this needs
> to be solved with this new product.
>
> Here's the approach I suggested to them - feel free to shoot it down.
> I've asked them to add a voltage divider before the regulator.  Run it
> through a Schmitt Trigger to an input pin on the '16.  I've also asked
> that they beef up the regulated voltage filtering to ensure at least 50
> mSec of adequate power to carry it through a total drop out of the
> supply.  (8.3 mSec, minimum, per EEPROM erase/write cycle times 3 bytes
> of data = 25 mSec ... then double it for peace of mind.)  Before writing
> the 1, 2, or 3 bytes of data, I'll check the status of the pin - if low,
> I won't do the write(s).
>
> I'm open to suggestions.  If you have a better approach or a
> bullet-proof algorithm, please enlighten me.
>
> Thanks!
>
> Gary.
>
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