LCD - Blocks at Start-up/Initialisation


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  1. #1
    Join Date
    Feb 2005
    Location
    Essex, UK
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    94

    Question LCD - Blocks at Start-up/Initialisation

    Hi,

    I am using a PIC16F877A to output to an LCD in 4 bit mode. For the 1/2 second start-up time needed before instructions can be sent to the LCD, I have blocks on the screen. I have noticed this when using other PICs as well and I realise that it is the test routine for the LCD and not the PIC. I am wondering if there is any way to eliminate this from being visible at start-up?

    Thanks

  2. #2
    Join Date
    Sep 2004
    Location
    montreal, canada
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    6,898

    Default

    disable the Vo line of your LCD. Vo is the contrast pin. Usually when you tie this pin to VCC you'll see Nothing
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  3. #3
    Join Date
    Feb 2005
    Location
    Essex, UK
    Posts
    94

    Thumbs up

    I was wondering about using the contrast line to achieve this.

    Thanks very much

    Rob

  4. #4
    Join Date
    Mar 2003
    Location
    Commerce Michigan USA
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    1,166

    Default

    Rob, Just tie the one side of a 10k pot to a spare micro pin of choice and the center of the pot to the VO line and the bottom of the pot to ground. Now with the pin outputing a high state adjust the pot for the correct contrast. Now during startup your code will output a low on the pin untill you want the display to be enabled and then just set it to a high state for display.

    HTH,
    Dave Purola,N8NTA

  5. #5
    Join Date
    Feb 2005
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    Essex, UK
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    94

    Default

    Originally posted by Dave
    Rob, Just tie the one side of a 10k pot to a spare micro pin of choice and the center of the pot to the VO line and the bottom of the pot to ground. Now with the pin outputing a high state adjust the pot for the correct contrast. Now during startup your code will output a low on the pin untill you want the display to be enabled and then just set it to a high state for display.

    HTH,
    Dave Purola,N8NTA

    Thanks for that - it works perfectly!

    Rob

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