Xtal transistor oscillator driving 2 PIC micros - 4 MHz

Discussion in 'Embedded Systems and Microcontrollers' started by atferrari, Nov 19, 2006.

  1. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
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    Initially I implemented a 4 MHz clock driving 2 PIC micros, using 2 inverters, one of them as a buffer (74HC04). To avoid the waste of space (the other 4 gates do nothing) I tried a transistor oscillator and buffer from an ARRL book but couldn't have it working. In my implementation space is at a premium.
    Can anyone show me a really working circuit?
    BTW: input should be a 4 MHz square wave or kind of a sine wave? If so, what pk to pk value? No experience on this.
    Thanks for any help.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Have you considered a clock oscillator IC? This is one from EPSON that comes in a 4.000 MHz version. They are available for around $3 from Digikey.

    hgmjr
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    Hi,

    The clock should be a square wave. Also, the clock oscillator that hqmjr mentions may be had in 1/2 size packages for tight spaces.
     
  4. pebe

    AAC Fanatic!

    Oct 11, 2004
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    I don't know which PIC you are using. If it has two pins OSCin and OSCout with the xtal between them and a cap from each to ground, then the 'in' pin will be high Z and the 'out' pin low Z.

    You can then wire direct from the OSCout of the first PIC to the OSCin of the second one.
     
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