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How much power does this draw?

  • mrbill Friday, July 13, 2012 7:39 AM Reply
    If I wanted to run this off a 9v battery - how much power would the backlight draw? Can you switch it off if necessary?
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  • Allegro1 Friday, July 13, 2012 10:22 AM Reply
    Haven't had a chance to do this, but the backlight is controlled by PWM on D10. You simply program D10 as a PWM output, then:

    analogWrite (10, fadeValue);


    Where fadeValue is 0-255, 0 being off 255 being max brightness

    It runs off of 5V which is regulated and supplied by the Arduino board. The backlight is a couple of white LED's so they don't draw very much power even when on.
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  • tekipui2 Tuesday, February 19, 2013 6:20 AM Reply
    is it necessary to put a Resistor (to limit the current) between Arduino pin 10 and LCD shield pin 10?
    I hope not, but I would like, please, a confirmation before use it. I don't want my Arduino be fried!!
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  • chopsuwe Thursday, January 12, 2017 5:43 PM Reply

    The resistor is necessary. My one had a 1k resistor under the LCD and was drawing over 120mA. A small modification will bring the current down to 5mA for the LCD + 18.mA for the backlight. It does require soldering. 


    For more information search the arduino.cc forum for the thread "Topic: Warning to users of some vendors LCD keypad shields." Post 153 is my experience with this board.

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