Are you using only 1 x 22pF ceramic ? Sounds like it from your reply. You should be using two - one leg of each capacitor to each of the two pins on the XTAL, the other side of both caps tied together and to earth. If you have 1 cap tied between the two legs of the XTAL, this is probably your problem ... Rgs Ian -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Jonnathan Partamian Sent: Monday, 24 February 2003 10:24 pm To: PICLIST@MITVMA.MIT.EDU Subject: Res: Re: [PIC]: Odd problem.... Thanks, I'll take a look on input pins the may be left floating. I'm using PIC18F452, 4MHz XTal with 22pF ceramic capacitor, all near to PIC. The MCLR is tyed to Vcc, WDT ok too. On Mon, 24 Feb 2003 14:19:12 +1100, Ian McLean wrote: Checklist for you... Also check the watchdog time is disabled in the config fuses colin 1) Check your configuration bits. In my experience though, this is usually not the problem, but the following are ... 2) Check that MCLR is tied HIGH. 3) Are you declaring any port as input, or leaving any pin defaulted to input, and leaving the pin floating ? This is a common problem with ICSP when those port B pins are not used for anything else (should in this case be tied LOW when not in use). 4) Check that the XTAL caps are correctly sized and tied to earth. They should be ceramic type. Check that your crystal and caps are as close to your PIC as possible. 5) Is the crystal you are using within spec. ? The caps need to be sized to fit the crystal you are using (check datasheet). -- cdb, bodgy1@optusnet.com.au on 24/02/2003 I have always been a few Dendrites short of an Axon and believe me it shows. Light travels faster than sound. That's why some people appear bright until they speak! -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body . -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body