is the clock signal measurable?

Discussion in '8bit Microcontrollers' started by Dr. Thomas Ansorg, Mar 10, 2009.

  1. Hello
    I have a 16f84 circuit with a 4Mhz clock signal (quartz), but I cannot
    measure this signal (on the oscilloscope). Is it possible to choose the
    wrong quartz or wrong type of capacitors?

    T.
     
    Dr. Thomas Ansorg, Mar 10, 2009
    #1
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  2. Dr. Thomas Ansorg

    WangoTango Guest

    In article <gp6cig$hhf$>, says...
    > Hello
    > I have a 16f84 circuit with a 4Mhz clock signal (quartz), but I cannot
    > measure this signal (on the oscilloscope). Is it possible to choose the
    > wrong quartz or wrong type of capacitors?
    >
    > T.


    Yes it is possible.

    You should have your scope on a 1meg input, 50 ohm will shut down the
    oscillator. You should be able to measure a 4MHz signal at the OSC2
    pin.

    You should use a parallel cut crystal NOT a series cut.
     
    WangoTango, Mar 10, 2009
    #2
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  3. "Geo" <> schrieb im Newsbeitrag
    news:...
    > On Tue, 10 Mar 2009 19:46:40 +0100, "Dr. Thomas Ansorg" <>
    > wrote:
    >
    >>I have a 16f84 circuit with a 4Mhz clock signal (quartz), but I cannot
    >>measure this signal (on the oscilloscope). Is it possible to choose the
    >>wrong quartz or wrong type of capacitors?

    >
    > Is it possible that the oscillator configuration bits could be programmed
    > incorrectly?


    Unlikely. The program I used was written by someone else, and it worked. How
    do I see whether the crystal is serial or parallel?

    T.
     
    Dr. Thomas Ansorg, Mar 12, 2009
    #3
  4. Dr. Thomas Ansorg

    WangoTango Guest

    In article <gpaekk$uj5$>, says...
    > "Geo" <> schrieb im Newsbeitrag
    > news:...
    > > On Tue, 10 Mar 2009 19:46:40 +0100, "Dr. Thomas Ansorg" <>
    > > wrote:
    > >
    > >>I have a 16f84 circuit with a 4Mhz clock signal (quartz), but I cannot
    > >>measure this signal (on the oscilloscope). Is it possible to choose the
    > >>wrong quartz or wrong type of capacitors?

    > >
    > > Is it possible that the oscillator configuration bits could be programmed
    > > incorrectly?

    >
    > Unlikely. The program I used was written by someone else, and it worked. How
    > do I see whether the crystal is serial or parallel?
    >
    > T.
    >
    >

    You really can't. It is something you specify when you order.
    If you can pull some kind of part number off the crystal and check that
    with the manufacturer, you might have a chance.
     
    WangoTango, Mar 12, 2009
    #4
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