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    LCD not working with External Oscillator

    Hi,

    I am using hd44780 4x20 LCD to display some data.. I am using PC30f5011 controller and external oscillator configured as XT Oscillator with PLL4X...
    its not showing any data only Back light is switching On.

    External Oscillator tested its working fine....

    Same code Configured as Internal Fast RC with PLL 16x LCD working fine.
    where i am missing plz let me know??

    I am using data pins from 49 -57 (RD0-RD7) you can refer from below attachment.

    External Oscillator -8Mhz
    Internal Oscillator -7.37Mhz

    Click image for larger version. 

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    Last edited by Thota Suresh Avionics; 10th February 2015 at 19:11.

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  2. #2
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    Re: LCD not working on External Oscillator

    check with delays with increased frequencies for what your project on display .



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  3. #3
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    Re: LCD not working with External Oscillator

    Quote Originally Posted by Thota Suresh Avionics View Post
    Hi,

    I am using hd44780 4x20 LCD to display some data.. I am using PC30f5011 controller and external oscillator configured as XT Oscillator with PLL4X...
    its not showing any data only Back light is switching On.

    External Oscillator tested its working fine....
    The terminology here is confusing.
    An external oscillator is a separate device that generates a clock that can be fed in to the OSC1 pin. For this to work, you need to select one of the EC oscillator modes.
    The XT (and HS and LP) oscillator modes require a crystal to be connected between the OSC1 and OSC2 pins (plus capacitors etc.).
    Both the EC and XT modes can be used with the PLL.
    When you say the "external oscillator [is] working fine", do you mean that you have an external oscillator running - in which case you must use an EC mode - or do you mean the crystal is oscillating (presumably you have put a scope on the OSC1 line).
    Perhaps of you tell us the FPR settings (and the perhaps the FOS bits as well) it will be clearer.
    Susan



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