On Sun, Aug 04, 2002 at 06:46:50PM +0300, =D6mer Yalhi wrote: > I have just ordered pic 18f452 and 40mhz xtals (without reading the man= ual). > do you mean to tell me that I wasted my money on the xtals?=20 Yup. That's what manuals are for. They won't work. > All I need is just a 10MHz xtal? Yup. > I don't get it... The part has a 4x PLL in it. So in HS/PLL mode it'll multiply the input clock signal by 4 giving up to 40 Mhz. BAJ >=20 > -----Original Message----- > From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.ED= U]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 40= mhz >=20 >=20 > OK I got this baby to run at 40MHZ. >=20 > Once you program with HS-PLL option you must shutdown the PIC (Reset wo= nt do > it) This allows the PLL to start up. >=20 > Some other observations. > When using crystals and resonators with PLL option the caps don't seem= to > make a difference. >=20 > In the 18FXX2 manual fig 2.6 does not show the use of caps. Any one kn= ow > any thing about this. >=20 > ----- 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 40= mhz >=20 >=20 > > The problem is the Chip does not run 4X internaly. A 10mhz crystal w= ith > 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 aga= in > they > > > > work fine at XT or HS as 10MHZ. But in HS/PLL they are still run= ning > 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 t= he > chip > > > get 4 times faster than HS mode? > > > > > > Lastly did you read the errata page for the 18C chips. There are so= me > > issues > > > on oscillator speed based on whether the chip is industrial or exte= nded. > > 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 > > > > > > >=20 > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu >=20 > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu >=20 -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu