LCD's and Sleeping Pics


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  1. #1
    Join Date
    May 2012
    Location
    Merseyside, UK
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    218

    Thumbs down LCD's and Sleeping Pics

    Hello

    Thank you for the quick read…. Posted this elsewhere by mistake :-)

    Is it deemed correct to drive a 16x20 LCD and back light direct from a single output Pin.

    Don't worry, when I say direct I "DO" mean via a Transistor or Darlington buffer….

    I am using an interrupt routine which will put the PIC to sleep…but the LCD is hung on the supply rails, The LCD will stay on, so was thinking if I hang it on a spare output port it can be shutdown before the PIC goes to sleep.

    Or is there a more elegant way of doing it??

    Thank you again

    Andy
    Last edited by andybarrett1; - 3rd August 2014 at 21:19. Reason: typo

  2. #2
    Join Date
    Sep 2008
    Location
    Maine, USA
    Posts
    81

    Default Re: LCD's and Sleeping Pics

    Andy,
    I *almost* always drive the back light with a separate pin via a MOSFET to have the option of PWM dimming of the light. If you have 2 pins to spare - 1 for LCD and 1 for BL. Many LCDs draw so little power that you can direct drive the LCD from an I/O pin. Check the power specs of your particular LCD or just use a MOSFET. My preferred MOSFET is the 2N7000 for up to 200mA or the BS170 for up to 500mA.
    "Do or do not, there is no try" Yoda

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