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Author Topic: Do not want to adjust LCD contrast  (Read 1491 times)
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Hi guys,

I do not want to adjust the contrast of my 16x2 LCD display.

Understand that usually a 10k potentiometer is used to connect to the V0 pin in the LCD if we want to control the contrast. But if I do not want to control the contrast, how and where should I connect the V0 pin to? Must I use a resistor to connect it instead of a potentiometer? If so, how do I determine the value of the resistor?
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Must I use a resistor to connect it instead of a potentiometer?

You can connect it a divider and experiment with the values to get the right divider ratio.

More pain than to connect it to a pot.
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I do not want to adjust the contrast of my 16x2 LCD display.
OK no one is forcing you to.
However do you want to see the display?
Then you will have to put in a pot, adjust it until it looks right. Remove the pot and measure the resistance from the wiper to each end. Then get the closest value to the measured ones and replace the pot with these.
Then hope that you don't need to adjust it again due to aging of the LCD or temperature changes.
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Another option is to just pwm a voltage to that pin. About 10% duty cycle in a 5v environment.

It allows the user to adjust contrast via software. It takes away, however, a resource.
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Thanks for the replies.

Looks like I'll just use the pot then.
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Thanks for the replies.

Looks like I'll just use the pot then.

A lot of beginners start with a rather large pot and they don't like using these pots for that reason. If you get one of the 3362 pots, it's breadboard friendly and small:

http://www.ebay.com/sch/i.html?_trksid=p2047675.m570.l1313&_nkw=3362+potentiometer&_sacat=0&_from=R40
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You could use a trimmer instead - set and forget kind of thing (but not quite a permanent as soldered in resistor pair in case you want to change it later)
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I'm using a 10k resistor from V0 to 5V and a 1,5K from V0 to GND.
Just try something similar and see if it looks ok.


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Alternatively if you want, purchase an OLED display that needs no contrast voltage adjustment.
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Most LCDs require a very low voltage (less than 0.5V) to give the best display but some perform adequately with 0V.  You might try connecting the contrast pin to GND and see how things look.

Don
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