Hi Peter,

You have a lot of experience with PICs, so this has got to be very
frustrating!

I know it may sound a little crazy or futile, but it might be worth
monitoring the WRERR flag in the EECON1 register -- it certainly would be
one more thing to rule out. I know what the WRERR flag is for and it *seems*
like your writes are not getting interrupted by a reset (from your
description of the problem), but it might be worth a try to light an LED if
WRERR gets set.

Also, as an isolated test case, have you tried an experiment of just using
100% assembly language for testing the EEPROM writes/reads? In other words,
don't use the C-compiler at all and just write a small ASM program in MPLAB
dealing with the EEPROM. This might shed some more light on your problem.

Is the C-compiler you are using "aware" of the errata? The HI-TECH PICC-18
compiler, I believe, seems to keep up with the errata docs and I think you
can turn this feature on/off. I'm not sure what C-compiler you are using.

Maybe a call or e-mail to Microchip Tech Support could get you on track --
responses to my e-mails usually come in the same day.

Good luck,

Ken Pergola







-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Peter Anderson
Sent: Monday, September 01, 2003 11:44 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC:] 18F1320 Data EEPROM


Thanks for the suggestions.

I am observing the errata sheet relative to reading
EEPROM.  The PICs I have are new.  I am seeing the
same thing on some five PIC18F1320s.

I started with a single write as I have done on every
other design using PICs (not the 18F1320).  Then, I
went to a write - read verify and found I had to
increase the number of tries to 500.  Crazy.

The PICs I am using are from May.  I have ordered
more, but this is a slim.

I am using the internal 4.0 MHz clock, which just
might be my problem.

If worse comes to worse I may have to revise the
design to store the data in flash memory.  This is for
an inexpensive LCD Kit where the LCD geometry, cursor
type, tab size and user defined characters are stored
in non-volatile memory, which change infrequently over
the life of the product.

Once again, thanks.

PHA, http://www.phanderson.com




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