I experienced this same problem.  The problem is that the software
assumes that the nonexistent config registers will be all ones.  This is
reasonable since most registers when erased read as ones.  However,
according to the datasheet for the 18F452 non-existent registers are red
as all zeros.  Also the config regesters are written two at a time.  My
solution was to do this:

;Config Settings
 __CONFIG _CONFIG1L, 0x000 				;nonexistant reg
 __CONFIG _CONFIG1H, _XT_OSC_1H & 0x027 ;b00100111 is def    
 __CONFIG _CONFIG2L, _PWRT_ON_2L & 0x00F  
 __CONFIG _CONFIG2H, _WDT_OFF_2H & 0x00F     
 __CONFIG _CONFIG4L, _LVP_OFF_4L & 0x085    
 __CONFIG _CONFIG4H, 0x000 				;nonexistant reg


Hope this helps,
Nathan Thomsen


-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of April Junkbox
Sent: Monday, May 09, 2005 9:14 PM
To: piclist@mit.edu
Subject: [PIC] Won't program fuses on 18F6621

I have a WISP628 programmer and I use Bumblebee V2 software. I have used

this combination successfully for a couple of years on several 16F628.
Now I 
am trying to program a 18F6621. I can program/read/verify the code, but 
whenever I try to program the fuses, it fails to verify. The values that
it 
reads back are completely different than what I sent, and completely 
different than all-zeros or all-ones. So, is there a trick to
programming 
the fuses on this device?

Thanks,
Gavin


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist