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'ceramic resonator'
1996\10\21@110024 by James Widman

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After hearing about the benefits of using a ceramic resonator from
the list I'm in need of some info.  Does anyone know where I can get
a data sheet (pdf would be great) for a Panasonic ceramic resonator
part #EFO-EC4004A4?  Or the pin out if data sheets are not available?

Thanks

Jim Widman
Fishery Biologist
spam_OUTjwidmanTakeThisOuTspamclam.mi.nmfs.gov

1996\10\21@130822 by mike

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In message  <.....199610211500.PAA09381KILLspamspam@spam@clam.mi.nmfs.gov> PICLISTspamKILLspamMITVMA.MIT.EDU
writes:
> After hearing about the benefits of using a ceramic resonator from
> the list I'm in need of some info.  Does anyone know where I can get
> a data sheet (pdf would be great) for a Panasonic ceramic resonator
> part #EFO-EC4004A4?  Or the pin out if data sheets are not available?
>

I generally use the 3 pin type with the built in caps. The two
outer pins get connected to osc1 and osc2. The middle pin gets
connected to GND or (of late 'cos the pcb layout is easier) VCC.


Regards,



Mike Watson

1996\10\21@155353 by Joe Freeman

picon face
At 11:00 AM 10/21/96 -0400, Jim Widman wrote:
>After hearing about the benefits of using a ceramic resonator from
>the list I'm in need of some info.  Does anyone know where I can get
>a data sheet (pdf would be great) for a Panasonic ceramic resonator
>part #EFO-EC4004A4?  Or the pin out if data sheets are not available?
>
>Thanks
>
>Jim Widman
>Fishery Biologist
>.....jwidmanKILLspamspam.....clam.mi.nmfs.gov

Digikey (800-DIGI-KEY) carries them; ask for part #PX400-ND.  According
to page 204 of their September-October catalog, the resonators cost all
of $0.86 (USD) each.  As Mike Watson <EraseMEmikespam_OUTspamTakeThisOuTd-m-g.demon.co.uk> mentioned,
the outer pins connect to OSC1 and OSC2, and the center pin connects to
GND.  Couldn't be easier, and the closest thing I've found to foolproof.

                                                       Good luck!
                                                       Joe

-- Joe Freeman                       Internet: joe.freemanspamspam_OUTmci.com
  MCI Communications / Austin       Work:    (512) 339-5337
  9001 North IH-35                  Fax:     (512) 339-5444
  Austin, TX 78753

1996\10\21@185549 by Henry Carl Ott

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At 05:53 PM 10/21/96 GMT, you wrote:

>
>I generally use the 3 pin type with the built in caps. The two
>outer pins get connected to osc1 and osc2. The middle pin gets
>connected to GND or (of late 'cos the pcb layout is easier) VCC.
>
>
>Regards,
>
>Mike Watson



I've also connected the center pin of ceramic resonators to VCC instead of
GND. However I've only done this with prototypes when it simplified the PCB
design.

Does anybody know if there is a problem with this practice in production
quantities? I'm wondering about stability and perhaps problems with the
oscillator starting.


Thanks

-carl

1996\10\21@221032 by Reginald Neale

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{Quote hidden}

If you have power supply traces bypassed really close to the chip, and the
bypasses have a very low impedance at the oscillator frequency, it probably
doesn't make much difference.


        Reg Neale         Usual disclaimer applies
"If absolute power corrupts absolutely, does absolute powerlessness make
you pure?". . . . ...Harry Shearer

1996\10\21@223002 by optoeng

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Henry Carl Ott wrote:
{Quote hidden}

You can connect it to any low DC potential: it's all the same to the
capacitors!  The important things are that the node to which it is
connected have a low impedance to ground at the oscillation frequency
and that the noise level not be too outrageously high.  In most cases, a
well-bypassed Vdd supply would meet these requirements.
--

Paul Mathews, consulting engineer
AEngineering Co.
@spam@optoengKILLspamspamwhidbey.com
non-contact sensing and optoelectronics specialists

1996\10\21@233939 by dfr

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Henry Carl Ott wrote:

>  I've also connected the center pin of ceramic resonators to VCC instead of
> GND. However I've only done this with prototypes when it simplified the PCB
> design.
>  Does anybody know if there is a problem with this practice in production
> quantities? I'm wondering about stability and perhaps problems with the
> oscillator starting.

Well, I suspect that others on this list may not agree with me, but I
would advise against it. Other than the obvious issue of VDD line noise
being introduced into the oscillator circuit, the small amount of
leakage current intoduced may cause some problems during start up under
marginal conditions. Now, before someone tells me that "thats not
likely" let me relate the following: 10+ years ago the Intersil 80C35
microcontroller used to have oscillator start up problems. The
recommended solution? Tie the caps to VCC instead of GND! I had to spec
out the part as we were unwilling to rework the PCB.

--
Regards, Dana Frank Raymond


'ceramic resonator'
1998\10\27@202752 by stephen mcalonan
picon face
Hello all,

I am new to this list and am having a problem with a ceramic resonator
and a pic16c74a.  I am using a 4Mhz panasonic resonator w/integral
caps(part# efo-s4004e5).  The resonator has an error of 0.5% and is
directly across osc1 and osc2.  Now on to the problem,  I noticed that
my rs232 communications at 4800 baud (0.16% error) were not reliable and
traced it back to the resonator.  I put a scope accross osc2 and ground.
My frequency was about 7Mhz!?  Should I place a series resistor before
osc2?  The pic data book mentions that one may be needed, but doesn't
get into specifics.  Any advice and help is greatly appreciated.

Thanks in advance,

Steve McAlonan
TBE-ES

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1998\10\27@213836 by Dave VanHorn

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stephen mcalonan wrote:
>
> Hello all,
>
> I am new to this list and am having a problem with a ceramic resonator
> and a pic16c74a.  I am using a 4Mhz panasonic resonator w/integral
> caps(part# efo-s4004e5).  The resonator has an error of 0.5% and is
> directly across osc1 and osc2.  Now on to the problem,  I noticed that
> my rs232 communications at 4800 baud (0.16% error) were not reliable and
> traced it back to the resonator.  I put a scope accross osc2 and ground.
> My frequency was about 7Mhz!?  Should I place a series resistor before
> osc2?  The pic data book mentions that one may be needed, but doesn't


Scoping the pins isn't too useful, as the scope loads the circuit.
Obviously there's no way you were running at 7, and only off .16% on
routines calculated for 4.  .16% also isn't enough to worry about on
serial.

To check your osc, one way is to tune it in on a shortwave radio. This
is nice, because it dosen't affect the circuit at all. Another would be
to program some output pin to make an output that's directly dependent
on the clock freq, like a timer output, or a large nop-loop and I/O
net/clear instructions.

AFAIK, you should be able to run serial at errors approaching 1% without
any trouble.  If your bitrate is accurate (look at AAh or 55h on a
scope) then I'd look very hard for other problems. Is it a software
uart? Level translators working right?

1998\10\27@231835 by Lee Jones

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>> I am new to this list and am having a problem with a ceramic resonator
>> and a pic16c74a.  I am using a 4Mhz panasonic resonator w/integral
>> caps(part# efo-s4004e5).  The resonator has an error of 0.5% and is
>> directly across osc1 and osc2.  Now on to the problem,  I noticed that
>> my rs232 communications at 4800 baud (0.16% error) were not reliable and
>> traced it back to the resonator.  I put a scope accross osc2 and ground.
>> My frequency was about 7Mhz!?  Should I place a series resistor before
>> osc2?  The pic data book mentions that one may be needed, but doesn't


> Scoping the pins isn't too useful, as the scope loads the circuit.
> Obviously there's no way you were running at 7, and only off .16% on
> routines calculated for 4.

> AFAIK, you should be able to run serial at errors approaching 1%
> without any trouble.


If you are using standard asynchronous serial with 10-bit frames
(1 start bit, 8 data bits, 1 stop bit), then your cumulative clock
mismatch for both ends can be almost 10% and still work correclty.

I'd check for flow control issues.  How do you know that it's "not
reliable"?  Is the PIC sending or receiving?  What's on the other
end of the serial link?
                                               Lee Jones

-------------------------------------------------------------------
Jones Computer Communications             KILLspamleeKILLspamspamfrumble.claremont.edu
509 Black Hills Dr, Claremont, CA 91711         voice: 909-621-9008
-------------------------------------------------------------------

1998\10\28@052421 by Russell McMahon

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Actually you are only allowed about 5% relative error between the two
ends as you can only get 1/2 a bit out (not one whole bit)  before
you are sampling in the wrong bit - the sampling starts in the middle
of the 1st bit after the leading edge of the start bit and must still
be inside the correct bit when the sample for the last data bit
arrives, 8.5 bit times later.

(1/2 bit) / (8.5 bits) ~ 5.8%


regards


   Russell McMahon

>If you are using standard asynchronous serial with 10-bit frames
>(1 start bit, 8 data bits, 1 stop bit), then your cumulative clock
>mismatch for both ends can be almost 10% and still work correclty.

1998\10\28@110109 by stephen mcalonan

picon face
>stephen mcalonan wrote:
>>
>> Hello all,
>>
>> I am new to this list and am having a problem with a ceramic
resonator
>> and a pic16c74a.  I am using a 4Mhz panasonic resonator w/integral
>> caps(part# efo-s4004e5).  The resonator has an error of 0.5% and is
>> directly across osc1 and osc2.  Now on to the problem,  I noticed
that
>> my rs232 communications at 4800 baud (0.16% error) were not reliable
and
>> traced it back to the resonator.  I put a scope accross osc2 and
ground.
>> My frequency was about 7Mhz!?  Should I place a series resistor
before
{Quote hidden}

without
>any trouble.  If your bitrate is accurate (look at AAh or 55h on a
>scope) then I'd look very hard for other problems. Is it a software
>uart? Level translators working right?
>
The stange thing is that when I use my emulator, using the external
oscillator, the RS232 works well.  I am only sending data (4800-8-N-1).
I only have occasional problems when I burn a chip and place it in my
target.  The rest of the programs works well.  I have a timer overflow
interupt in my program and an available output pin.  I will toggle the
output pin and view that on the scope.  Thanks for the suggestion.
-Steve

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1998\10\28@110448 by stephen mcalonan

picon face
>>> I am new to this list and am having a problem with a ceramic
resonator
>>> and a pic16c74a.  I am using a 4Mhz panasonic resonator w/integral
>>> caps(part# efo-s4004e5).  The resonator has an error of 0.5% and is
>>> directly across osc1 and osc2.  Now on to the problem,  I noticed
that
>>> my rs232 communications at 4800 baud (0.16% error) were not reliable
and
>>> traced it back to the resonator.  I put a scope accross osc2 and
ground.
>>> My frequency was about 7Mhz!?  Should I place a series resistor
before
>>> osc2?  The pic data book mentions that one may be needed, but
doesn't
{Quote hidden}

The pic is only sending data (4800-8-N-1).  I have hyperterminal running
on a pc. The stange thing is that when I use my emulator, using the
external oscillator, the RS232 works well.  I only have occasional
problems when I burn a chip and place it in my target.  The pic is
supposed to dump some data every second (about 100 chars).  The rest of
the programs works well.
Best regards,
Steve

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1998\10\30@020609 by stephen mcalonan

picon face
>stephen mcalonan wrote:
>>
>> Hello all,
>>
>> I am new to this list and am having a problem with a ceramic
resonator
>> and a pic16c74a.  I am using a 4Mhz panasonic resonator w/integral
>> caps(part# efo-s4004e5).  The resonator has an error of 0.5% and is
>> directly across osc1 and osc2.  Now on to the problem,  I noticed
that
>> my rs232 communications at 4800 baud (0.16% error) were not reliable
and
>> traced it back to the resonator.  I put a scope accross osc2 and
ground.
>> My frequency was about 7Mhz!?  Should I place a series resistor
before
{Quote hidden}

without
>any trouble.  If your bitrate is accurate (look at AAh or 55h on a
>scope) then I'd look very hard for other problems. Is it a software
>uart? Level translators working right?
>

Thank you all for your help.  The resonator is working correctly.  I
just had a bad comm port on the PC that I was using.  I swapped from
Comm 1 to Comm2 with good results.  Thanks again.

-Steve McAlonan

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