Connect with us

AVR, external clock

Discussion in 'Electronic Basics' started by Umpa, May 13, 2004.

Scroll to continue with content
  1. Umpa

    Umpa Guest

    Hello,

    I have got AVR ATmega16.

    I`m developing an application
    which should receive data from
    UART.
    I would like to conntec external
    oscilator of 11059200 Hz.
    I connected it to XTAL and set
    fuse "ext. clock", but processor
    doesn`t work.

    What to do to make my processor
    working with external oscilator
    and using it for UART?

    Umpa.
     
  2. Anders

    Anders Guest

    What type of XTAL is it ?
    What input pins are you using ?

    /Anders
     
  3. Umpa

    Umpa Guest

    What type of XTAL is it ?
    It is cristal oscilator 11059200Hz
    I am using XTAL1 and XTAL2.
     
  4. Anders

    Anders Guest

    OK
    Have you connected 2 capacitors to the XTAL ?
    22-33pF is mostly used, look in the datasheet.
    / Anders
     
  5. Umpa

    Umpa Guest

    Have you connected 2 capacitors to the XTAL ?
    Yes. Two capacitors of 27pF connected to XTAL1
    and XTAL2 and GND.

    Test:

    I connected 8MHz oscilator, set fuse XTAL3-8MHz.
    It works.

    I connected 11MHz oscilator, set fuse XTAL3-8MHz.
    Doesn`t work.

    I connected 11MHz oscilator, set fuse XTAL3-8MHz,
    changed state of !CKOPT.
    Doesn`t work

    I tried a few 11MHz oscilators.

    If I use oscilator slower than 8MHz there are fuses that
    cover it (XTAL3-8, XTAL...)

    But my oscilator is 11MHz. Atmel`s manual says that
    we should change CKOPT for oscilators faster than 8MHz.
    But it doesn`t help.

    Umpa.
     
  6. Anders

    Anders Guest

    Is it at MEGA16 or a MEGA16L ?
     
  7. Umpa

    Umpa Guest

    Is it at MEGA16 or a MEGA16L ?

    I have got ATmega16. Without "L".
    Any idea about my problem ?

    Umpa.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-