Crystal ossilator to second chip...


Closed Thread
Results 1 to 4 of 4
  1. #1

    Default Crystal ossilator to second chip...

    I have a board from olimex with a 20mhz crystal... I want to tap the signal and use it to drive another chip. I plan to run a wire from OSC2/PIN14, but I can't test until I get the other chip out of its board (its the IR cam from the Wiimote) next Wednesday. I have attached the schematic of the board. Can anyone tell me if my thinking is correct?

    Here config settings for the pic18f4550
    __CONFIG _CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
    __CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H
    __CONFIG _CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L & _BORV_2_2L & _VREGEN_ON_2L
    __CONFIG _CONFIG2H, _WDT_OFF_2H
    __CONFIG _CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H & _CCP2MX_ON_3H
    __CONFIG _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _ICPRT_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L
    Attached Images Attached Images  

  2. #2
    Join Date
    Feb 2009
    Location
    Southern California
    Posts
    86


    Did you find this post helpful? Yes | No

    Default

    I have run up to 5 micros with one crystal, but they are all very close together, so don't try to extend a wire too far. When I did it I shared both pins 13 and 14 between the chips, not sure if that really matters or not.

  3. #3
    Join Date
    Aug 2006
    Location
    Look, behind you.
    Posts
    2,818


    Did you find this post helpful? Yes | No

    Default

    to get more drive on that OSC out line you could buffer with an inverter . . .
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
    .
    Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
    .
    There simply is no "Happy Spam" If you do it you will disappear from this forum.

  4. #4


    Did you find this post helpful? Yes | No

    Thumbs up

    I asked the question because I didn't understand how the crystals work and what the difference is to the resonators...As far as I understand now, the crystal amplifies ac noise at its resonant frequency at startup until everything is in synch with its resonant frequency...So there's a 5volt AC signal present there? I'm guessing I could pull one line into the comparator, and use the comparator output...Would that help to extend the wire?
    greets,
    Mike

Similar Threads

  1. Sharing Crystal with 2 IC's
    By ShaneMichael in forum mel PIC BASIC Pro
    Replies: 5
    Last Post: - 10th January 2013, 13:33
  2. TV Display Chip
    By zadok in forum mel PIC BASIC Pro
    Replies: 19
    Last Post: - 17th April 2008, 22:17
  3. 20 Mhz Crystal, simple blinking LED
    By BenjaminsShinob in forum mel PIC BASIC Pro
    Replies: 5
    Last Post: - 16th October 2007, 05:06
  4. chip selection aid
    By PICMAN in forum General
    Replies: 4
    Last Post: - 21st February 2005, 18:33
  5. Replies: 1
    Last Post: - 30th June 2004, 08:07

Members who have read this thread : 1

You do not have permission to view the list of names.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts