OK, just for the record.. RTFM should always be the first step. I try to, at least. Your posting and the ensuing discussion were valuable to me. I also purchased some 40MHZ XTals in anticipation of my recently arrived PIC18F parts. Had I not read your post, I would surely have fallen into the same predicament. This morning I read the manual(41159a.pdf), and while an=20 explanation of the PLL feature was there, there was no statement that it is required. Granted, the tables show testing of resonators and crystals only up to 25MHZ, and only up to 10 with HS4 enabled.. But there was nothing that I read stating that you couldn't do regular HS at 40 MHZ. Also, the higher clock rates in the table were marked "TBD" or something similar. Perhaps I'm using a dated datasheet. I DL'ed the latest, sure enough, this was updated to 41159b.pdf. Still marked as "preliminary", but apparently the latest as I just got it from the Microchip website. The "Oscillator Options" are the same. Am I looking in the wrong place? In the wrong document? Is it just a Monday thing? Any feedback, corrective or otherwise, is welcomed. Lyle Hazelwood -----Original Message----- From: Josh Koffman [mailto:listsjosh@3MTMP.COM] Sent: Monday, August 05, 2002 1:29 PM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [PIC]:Has any one ever got a PIC 18F244 chip to work at 40mhz Ok, admittedly I slipped on this one. I shouldn't have asked. Sorry all. Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams Olin Lathrop wrote: -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads