Re: Routing signals under crystals

From	rickman <gnuarm@gmail.com>
Newsgroups	comp.arch.embedded
Subject	Re: Routing signals under crystals
Date	2013-08-27 12:49 -0400
Organization	A noiseless patient Spider
Message-ID	<kvilb4$7v5$1@dont-email.me> (permalink)
References	(3 earlier) <MPG.2c81200ab1cde9329896ba@news.eternal-september.org> <kvame9$tg8$1@dont-email.me> <87a9k6wlmn.fsf@digitalsignallabs.com> <kvdove$5v5$1@dont-email.me> <87sixxtg8o.fsf@digitalsignallabs.com>

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On 8/25/2013 9:04 PM, Randy Yates wrote:
> rickman<gnuarm@gmail.com>  writes:
>
>> On 8/24/2013 10:27 PM, Randy Yates wrote:
>>> rickman<gnuarm@gmail.com>   writes:
>>>
>>>> On 8/24/2013 1:16 AM, Mark Borgerson wrote:
>>>>>
>>>>> I agree with that.   It's probably even less of a problem when the
>>>>> fastest clock on the board is in the internal processor of the
>>>>> SD card logging the data.  Writing to an SD card can generate quite
>>>>> a burst of EMI,  but I haven't seen large effects on crystal behavior.
>>>>
>>>> Really?  I've never seen significant EMI directly generated by any
>>>> chip.
>>>
>>> How do you know where it's coming from? Do you have screen rooms,
>>> antennae, spectrum analyzers, etc., like FCC testing centers do?
>>
>> Lol, if you have EMI, you fix the board and it goes away, that shows
>> it wasn't the chip...  Same with the SD card.  Replace the SD card
>> with a different brand and the EMI should change or go away.
>
> Sure. But remember all those funny interactions you were talking about?

No, I don't.  The point is that if the chip were faulty you would not be 
able to fix it in the board.  If you can design a board that limits the 
EMI of the design, then by definition the problem is not the chip.

Are you suggesting that the board could be designed in a way that it 
creates EMI that emanates from the chip?  My point is that the chip or 
SD card can be used in a design so that doesn't generate EMI or the chip 
generates EMI no matter what you do.  I don't really care what ends up 
being the antenna because that is a pointless distinction.

-- 

Rick

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Routing signals under crystals Luis Filipe Rossi <luisf.rossi@gmail.com> - 2013-08-22 10:33 -0700
  Re: Routing signals under crystals Tim Wescott <tim@seemywebsite.really> - 2013-08-22 16:25 -0500
    Re: Routing signals under crystals upsidedown@downunder.com - 2013-08-23 09:35 +0300
      Re: Routing signals under crystals Tim Wescott <tim@seemywebsite.really> - 2013-08-23 12:43 -0500
  Re: Routing signals under crystals Richard Damon <Richard@Damon-Family.org> - 2013-08-22 21:45 -0400
    Re: Routing signals under crystals MK <mk@nospam.co.uk> - 2013-08-23 08:40 +0100
      Re: Routing signals under crystals Mike Perkins <spam@spam.com> - 2013-08-23 11:05 +0100
        Re: Routing signals under crystals Luis Filipe Rossi <luisf.rossi@gmail.com> - 2013-08-23 04:55 -0700
          Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-23 16:10 -0400
          Re: Routing signals under crystals Clifford Heath <no.spam@please.net> - 2013-08-24 09:55 +1000
            Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-23 20:23 -0400
              Re: Routing signals under crystals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-24 09:41 +0100
                Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-24 12:10 -0400
                Re: Routing signals under crystals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-24 17:21 +0100
                Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-24 12:53 -0400
              Re: Routing signals under crystals Clifford Heath <no.spam@please.net> - 2013-08-24 23:11 +1000
            Re: Routing signals under crystals Don Y <this@isnotme.com> - 2013-08-23 19:43 -0700
      Re: Routing signals under crystals Richard Damon <Richard@Damon-Family.org> - 2013-08-24 00:34 -0400
      Re: Routing signals under crystals Mark Borgerson <mborgerson@comcast.net> - 2013-08-23 22:16 -0700
        Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-24 12:19 -0400
          Re: Routing signals under crystals Mark Borgerson <mborgerson@comcast.net> - 2013-08-24 09:59 -0700
          Re: Routing signals under crystals Randy Yates <yates@digitalsignallabs.com> - 2013-08-24 22:27 -0400
            Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-25 16:20 -0400
              Re: Routing signals under crystals Randy Yates <yates@digitalsignallabs.com> - 2013-08-25 21:04 -0400
                Re: Routing signals under crystals rickman <gnuarm@gmail.com> - 2013-08-27 12:49 -0400

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