I had a project where I had to replace the resonator with a clock chip. Worked fine at room temperature but in the factory environment, a 10 degree drop in temperature caused the usb circuit to fail. My advice: use a XTAL. Bob Ammerman wrote: > I stand corrected. I must of been thinking of an earlier USB chip (or > another vendor). > > -- Bob Ammerman > RAm Systems > > ----- Original Message ----- > From: "Peter van Hoof" > To: "Microcontroller discussion list - Public." > Sent: Wednesday, October 28, 2009 11:30 PM > Subject: Re: [PIC] 18F4550 resonator for USB? > > > >>I use a 20MHz Quartz Crystal with a 4550 for USB in one of my projects >> >> >>This works fine with these settings: >> >>_PLLDIV_5_1L = divide by 5 >>_CPUDIV_OSC1_PLL2_1L = primary oscilator used directly for system clock >>_USBDIV_2_1L = USB clock from 96 MHz pll divided by 2 >>_FOSC_HS_1H = HS oscilator >> >>Peter >> >> >> >>----- Original Message ---- >> >>>From: Bob Ammerman >>>To: Microcontroller discussion list - Public. >>>Sent: Wed, October 28, 2009 11:00:26 PM >>>Subject: Re: [PIC] 18F4550 resonator for USB? >>> >>>Haven't looked at it for some time, but doesn't he need to use a 6MHz >>>XTAL >>>with PLL to do USB? Or a 24MHz XTAL, I guess. >>> >>>20 MHz won't work because the USB SIE requires a 24MHz clock, IIRC. >>> >>>-- Bob Ammerman >>> >>>----- Original Message ----- >>>From: "Peter van Hoof" >>>To: >>>Sent: Wednesday, October 28, 2009 9:58 PM >>>Subject: [PIC] 18F4550 resonator for USB? >>> >>> >>> >>>>Greetings to all. >>>> >>>>A friend has started building a circuit with a 18F4550 and a 20 MHz 3 >>>>pin >>>>ceramic resonator. >>>>Is a resonator accurate enough to allow USB communication or does he >>>>need >>>>a quartz? >>>> >>>> >>>>Peter van Hoof >>>> >>>> >>>> >>>> >>>>-- >>>>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 >> >> >> >> >>-- >>http://www.piclist.com PIC/SX FAQ & list archive >>View/change your membership options at >>http://mailman.mit.edu/mailman/listinfo/piclist > > > > ------------------------------------------------------------------------ > > > Internal Virus Database is out of date. > Checked by AVG - http://www.avg.com > Version: 8.0.176 / Virus Database: 270.14.29/2455 - Release Date: 10/24/2009 6:43 AM > -- Donald C. Parker, Keystone Applications, Brooklyn, WI Phone: 608-835-9264 Primary Inet: dparker@execpc.com Secondary: parker@acm.org WWW: http://my.execpc.com/~dparker/ Feb. 28: Near Waco, Texas, agents of the Bureau of Alcohol, Tobacco and Firearms, suspecting firearms violations in the Branch Davidian compound, smoothly execute an action plan masterminded by Wile E. Coyote. Dave Barry, 1993 in Review -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist