I have just ordered pic 18f452 and 40mhz xtals (without reading the manual). do you mean to tell me that I wasted my money on the xtals? All I need is just a 10MHz xtal? I don't get it... -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Michael Simpson Sent: Sunday, August 04, 2002 11:13 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [PIC]:Has any one ever got a PIC 18F244 chip to work at 40mhz OK I got this baby to run at 40MHZ. Once you program with HS-PLL option you must shutdown the PIC (Reset wont do it) This allows the PLL to start up. Some other observations. When using crystals and resonators with PLL option the caps don't seem to make a difference. In the 18FXX2 manual fig 2.6 does not show the use of caps. Any one know any thing about this. ----- Original Message ----- From: "Michael Simpson" To: Sent: Sunday, August 04, 2002 2:11 AM Subject: Re: [PIC]:Has any one ever got a PIC 18F244 chip to work at 40mhz > The problem is the Chip does not run 4X internaly. A 10mhz crystal with HS > and PLL does not run internaly at 40MHZ. > > > ----- Original Message ----- > From: "Byron A Jeff" > To: > Sent: Saturday, August 03, 2002 6:56 PM > Subject: Re: [PIC]:Has any one ever got a PIC 18F244 chip to work at 40mhz > > > > On Sat, Aug 03, 2002 at 05:46:16PM -0400, Michael Simpson wrote: > > > The question is for the PLL option I am using a 10MHZ Resonator. IT > works > > > at 10MHZ with or with out the PLL option. > > > > > > As far as the crystals I have tried about 20 brands and types. I > purchased > > > about 10 each a few weeks ago so I could test. At the lower > frequencies > > > they all seem to work. fine. I have a few 10mhz crystals and again they > > > work fine at XT or HS as 10MHZ. But in HS/PLL they are still running at > > > 10MHZ. > > > > (sound of head scratching...) > > > > They are supposed to run at 10 Mhz. So what exactly is the problem? > > > > The PLL is internal and uses the 10 Mhz external signal to generate the 40 > Mhz > > clock internally. So there should be no change in the external appearance > of > > the external oscialltor. > > > > It's supposed to run at 10 Mhz. > > > > So I only have one question: When you enabled the HS/PLL mode did the chip > > get 4 times faster than HS mode? > > > > Lastly did you read the errata page for the 18C chips. There are some > issues > > on oscillator speed based on whether the chip is industrial or extended. > Take > > a read if you get a chance... > > > > BAJ > > > > -- > > 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 hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu