18F4550 resonator for USB?
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18F4550 resonator for USB?
by Peter van Hoof-2
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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 |
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Re: 18F4550 resonator for USB?
by Matt Callow
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2009/10/29 Peter van Hoof <pvhoof@...>:
> 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 > I've not tried it myself, but the USB Bit Whacker uses a ceramic resonator. See http://www.schmalzhaus.com/UBW/ Matt -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist |
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Re: 18F4550 resonator for USB?
by Bob Ammerman
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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" <pvhoof@...> To: <piclist@...> 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 |
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Re: 18F4550 resonator for USB?
by Christopher Head-4
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The SIE requires a 48MHz clock. The PLL runs at 96MHz and divides by
2 to provide the SIE clock. The PLL can be driven by many different frequencies (including 20MHz) through the use of the divider. This is assuming full-speed operation. Chris On Wed, 28 Oct 2009 23:00:26 -0400 "Bob Ammerman" <rammerman@...> wrote: > 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 > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist |
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Re: 18F4550 resonator for USB?
by Peter van Hoof-2
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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 <rammerman@...> > To: Microcontroller discussion list - Public. <piclist@...> > 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 |
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Re: 18F4550 resonator for USB?
by Forrest W Christian-2
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Not 100% certain about the ceramic resonators, but I do know that the
new PIC18f26J50's claim to have an accurate enough intosc to be able to do away with any external oscillator at all. The datasheets often will discuss the clock accuracy needed, IIRC. Look in the oscillator section and also in the USB section of the datasheet. -forrest Peter van Hoof wrote: > 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 |
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Re: 18F4550 resonator for USB?
by Wouter van Ooijen
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> 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? I did use a resonator in an early version of my pickit2 clone and did encounter some problems. I am not sure they were caused by the resonator but they might. -- Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: www.voti.nl/hvu -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist |
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Re: 18F4550 resonator for USB?
by Bob Ammerman
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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" <pvhoof@...> To: "Microcontroller discussion list - Public." <piclist@...> 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 <rammerman@...> >> To: Microcontroller discussion list - Public. <piclist@...> >> 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 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist |
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Re: 18F4550 resonator for USB?
by Don Parker-3
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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" <pvhoof@...> > To: "Microcontroller discussion list - Public." <piclist@...> > 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 <rammerman@...> >>>To: Microcontroller discussion list - Public. <piclist@...> >>>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@... Secondary: parker@... 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 |
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Re: 18F4550 resonator for USB?
by Barry Gershenfeld-2
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A resonator is good enough if you stick to Low Speed (the 1.2M-bit mode).
Good enough for a mouse, apparently. Historically, resonators aren't good enough for Full Speed and up. This probably means that for hobby use, you might get lucky, but if you build several of them, only some of them will work. Or sometimes they will work. I've had a few USB devices that occasionally drop off line, and suspect it's related to a not-quite-close-enough clock generator. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist |
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