Folks:

Is there any trick to getting EEPROM to read/write under MPLAB with 
C18?  Until recently I've been working with the 16 series and have not had 
any problems reading/writing EEPROM both with C (CCS) and with assembly 
language.  However I'm having trouble getting data to either read or write 
with C18.  Here's my configuration:

MPLAB  6.52
C18 (latest version)
ICD-2
18F252

I've got all code/data protection turned off.  I'm trying the following 
code (in C18):

   EEADR =0x01;   	//write to address 1
   EEDATA = 0x33; 	//write the data value 33h
   EECON1bits.EEPGD = 0;    //write to eeprom, not flash program memory
   EECON1bits.WREN = 1;      //allow writes
   EECON2 = 0x55;
   EECON2 = 0xAA;
   EECON1bits.WR = 1;  	//do the write
   while (EECON1bits.WR);    //wait until done
   EECON1bits.WREN = 0;    //write enable off

This is essentially all the code in the program... so I've not worried 
about disabling interrupts (though I tried that too).  When I step through 
this code in the debugger, I see the register changes that are expected, 
except register EECON2 does not change.  I'm assuming this is because the 
datasheet says this register doesn't really exist and will always read 
0.  Yet after I run this code, I examine the contents of the EEPROM (in 
MPLAB) and register 1 is still 0xFF.  If I change the register manually in 
the EEPROM window of MPLAB, write the data and then read back the data 
(using program and read) the register does change, so I assume there must 
be a problem with my code.

Anybody see what I'm doing wrong here?

Thanks,

John Hansen


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