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Topic: LCD pin connection (Read 1 time) previous topic - next topic

floresta

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Ok,i wired everything like this link http://arduino.cc/en/Tutorial/LiquidCrystal

i run the example 'Hello,world' and everything was fine except the fact that the backlight doesn't work.


The display in the example does not have power connected to the backlight and neither does yours.  The backlight is completely independent of the actual display and therefore the contrast adjustment has nothing to do with the visibility of the backlight.

Try connecting a 150 ohm resistor between +5V and pin 15 and connect pin 16 to GND and see if your backlight comes to life.


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i must tell you that i used a 4.7K potentiometer (instead of 10K in the example)


This is fine as far as the LCD is concerned.  You are drawing more current from your power supply than you would with a larger potentiometer.  If you have a 20K or 50K pot one of those would be a better choice.

You probably should brush up on your soldering skills.


Don

Docedison

A 4K7 potentiometer draws a little over a milliamp @ 5Vdc, a 10 K one half of that and the green power LED on the board draws 3.4 milliamp and yes the Vee pin draws no current to speak about....
Where here are the savings??? Compared to what? I do understand both sides of the issue and it is my point that there are somethings that don't need fixing and aren't changed enough to make the changes worthwhile. The chances of making an error on a "Working" assembly trying to save 500 uA seems to be of dubious merit. In fact the chance that an error might very well happen during such a change would IMO make the change highly questionable, if Still not I ask myself what is the advantage in saving a couple of hundred microwatts of power. There is also the thought that such a change in current could not be measured by the Arduino easily either...

Doc
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

floresta

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there are somethings that don't need fixing


I didn't say that there was anything that needed fixing.  I merely pointed out that another solution would have been a better choice.


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The chances of making an error on a "Working" assembly trying to save 500 uA seems to be of dubious merit.


The chances of making an error by pulling one potentiometer out of a breadboard and replacing it with another one are pretty slim.  Any errors made would be immediately apparent and would not likely result in any damage.

Don

wizer

The LCD now is working properly.Thank you very much for your help.I'm grateful to you!

Docedison

The operating thought here is not likely... rephrased... Wanna Bet? If you don't touch it you didn't break it maybe. It has been my experience for far longer than I like to think that the less handling of any item the less chance for an inadvertent 'something' to happen. Yes I err frequently but at least some of my errors are now due to an excess of caution. Electronically I am Very conservative and in my old age I still brick things but quite a bit less often, now.

Doc
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

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