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'[PIC]: PIC16F877 not working with 20.0 MHz Resonat'
2001\06\21@011144 by Donovan Parks

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Hello,

I am using a PIC16F877 - 20/P and wish to use a 20.0 MHz resonator with it.
I am using a ECS Inc. ZTT-20.00MX resonator.  It has build in capacitors and
thus I am connected it directly to the PIC, but the PIC doesn't work.  I
have a 4.0 MHz resonator (says ZTT on it) and the PIC works with it.  Any
suggestions?  Is there anything that needs to be changed when swapping
resonators?  I am testing with a simple piece of code that blinks an LED at
1s (though this would be much faster at 20MHz).

Thanks,
Donovan Parks

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2001\06\21@031952 by Patrick J

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You should set the oscillator option to HS (high speed) when programming it
instead of XT. Also u may need to switch the pins osc1 osc2 it connects to.


{Original Message removed}

2001\06\22@005853 by jay

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Tom, make sure that you've chosen the "High Speed" (HS) option when burning the chip.
Jason Mielke
Chief Engineer
Bliss Communications, Inc.
spam_OUTjayTakeThisOuTspamlinuxforbroadcasters.com
http://www.linuxforbroadcasters.com



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2001\06\22@090753 by Olin Lathrop

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> I am using a PIC16F877 - 20/P and wish to use a 20.0 MHz resonator with
it.
> I am using a ECS Inc. ZTT-20.00MX resonator.  It has build in capacitors
and
> thus I am connected it directly to the PIC, but the PIC doesn't work.  I
> have a 4.0 MHz resonator (says ZTT on it) and the PIC works with it.

Did you remember to set the oscillator mode to HS for 20MHz?


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, .....olinKILLspamspam@spam@embedinc.com, http://www.embedinc.com

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2001\06\22@091534 by myke predko

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Hi Donovan,

I've found that 16 MHz or higher ECS oscillators with internal caps do NOT
work with ANY PICmicros.  The built in 30 pF capacitance is too high.

Take a look at Panasonic's resonators (with 20 pF built in capacitors or
less) or use the ECS oscillators which do not have built in caps and add
your own external 15-22 pF caps.

Good luck,

myke
{Original Message removed}

2001\06\22@101051 by Dan Michaels

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Donovan Parks wrote:
>Hello,
>
>I am using a PIC16F877 - 20/P and wish to use a 20.0 MHz resonator with it.
>I am using a ECS Inc. ZTT-20.00MX resonator.  It has build in capacitors and
>thus I am connected it directly to the PIC, but the PIC doesn't work.  I
>have a 4.0 MHz resonator (says ZTT on it) and the PIC works with it.  Any
>suggestions?


Donovan, I personally have never had any success getting PICs
to work with resonators at >= 16 mhz. OTOH, crystals always work
for me, and cost as little as $0.60. Also, use smaller caps for
higher frequencies. I use 18pF @ 20 mhz.

best regards,
- dan michaels
http://www.oricomtech.com
===========================

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2001\06\22@123929 by Harold M Hallikainen

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On Fri, 22 Jun 2001 10:10:51 -0400 Dan Michaels <oricomspamKILLspamUSWEST.NET>
writes:
>
> Donovan, I personally have never had any success getting PICs
> to work with resonators at >= 16 mhz. OTOH, crystals always work
> for me, and cost as little as $0.60. Also, use smaller caps for
> higher frequencies. I use 18pF @ 20 mhz.
>

       I have thousands of systems out using murata 16 MHz resonators with
built-in capacitors. Murata actually characterizes the resonators for
each microcontroller. I've talked with various other resonator companies,
and they say that if the resonator works in their sample circuit (a cmos
inverter circuit), the resonator meets specs. Of course it doesn't work
with the PIC. So, we just buy murata and they work every time!  Check out
the murata web site. They have a search engine where you can put in the
chip number and they'll give you a part number for the resonator that
will work.


Harold


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2001\06\22@124958 by Raymond Choat

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Did you change your Oscillator to HS before programming?
Wrong Way Ray (Raymond Choat)

----- Original Message -----
From: "Donovan Parks" <.....dparksKILLspamspam.....UVIC.CA>
To: <EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU>
Sent: Wednesday, June 20, 2001 8:36 PM
Subject: [PIC]: PIC16F877 not working with 20.0 MHz Resonator


> Hello,
>
> I am using a PIC16F877 - 20/P and wish to use a 20.0 MHz resonator with
it.
> I am using a ECS Inc. ZTT-20.00MX resonator.  It has build in capacitors
and
> thus I am connected it directly to the PIC, but the PIC doesn't work.  I
> have a 4.0 MHz resonator (says ZTT on it) and the PIC works with it.  Any
> suggestions?  Is there anything that needs to be changed when swapping
> resonators?  I am testing with a simple piece of code that blinks an LED
at
{Quote hidden}

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2001\06\22@175548 by M. Adam Davis

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Something every electronics person should keep in mind is that
breadboards are severely capacitive.  Oh sure, that's not a problem for
slow stuff, but you may find the capacitance between to terminals of a
really bad breadboard to be 2, 7, or even as much as 20pf!  This,
obviously, would mess with all your projects, but it's not too
noticeable until you deal with above 10MHz signals, or you're dealing
with audio stuff, where minor capacitance is bothersome.

If you must use 20MHz, use a PCB (such as the pre-made prototyping pcbs
available at radioshack, etc)

At minimum socket and mount the chip and resonator, then you can use
connectors to wire to a breadboard for easier prototyping.  If you use a
wire-wrap socket for the chip, then you can put it on the pcb with the
long pins sticking out below, clip off the oscillator pins, and use it
in a breadboard just as you would have used it without a pcb.

Others have mentioned other problems you might see (too high of a
capacitance, oscillator setting type, etc)

-Adam

Donovan Parks wrote:

{Quote hidden}

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'[PIC]: PIC16F877 not working with 20.0 MHz Resonat'
2001\07\10@163345 by Andre Abelian
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1. try changing XT to HS .
2. try adding series resistor on OSC2  pin or 10k pot and slowly
   turn it ?
3. make sure your master clear pin do not have higher then 0.01 mf cap
   and your 5v is clean.

Andre Abelian

{Quote hidden}

> {Original Message removed}

2001\07\11@121916 by Harold M Hallikainen

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       Use resonators from murata. I have thousands of units out with 16 MHz
resonators with internal capacitors. They connect directly to the PIC
pins with no other wiring. I had trouble with ECS and other resonators.
Talking to ECS, they said that if it worked in their sample circuit
(based on a CMOS inverter), the resonator was fine. The problem was our
circuit (over which we have very little control). Murata, on the other
hand, will characterize resonators for use directly with various micros.
Check their website for the micro search engine.

Harold


On Wed, 11 Jul 2001 01:03:00 -0700 Andre Abelian <engelecspamspam_OUTEARTHLINK.NET>
writes:
{Quote hidden}

> > {Original Message removed}

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