HD44780 16x2 LCD won't work with my Uno

Other Hardware Displays
1

Hi guys,

I have this HD44780 16x2 LCD and my arduino uno, im following this guide trying to wire it up with a 10k potentiometer:

I get the lcd backlight on but the resistor does nothing, i tried changing it with other 1K and 100K resistors and still no effect.

Help please?

Picture of the setup, sorry if its a bit messy:

Sharon

2

Make sure you have the same pin out as in that tutorial, take your time reading the following tutorial:

http://tronixstuff.wordpress.com/2011/01/08/tutorial-arduino-and-monochrome-lcds/

3

I just wired up my first LCD panel today. I too could not get it to work until I followed the example at Arduino Character LCD Tutorial. The 16x4 LCD I am using is this one http://imall.iteadstudio.com/eone-high-cost-effective-1604-characters-lcd-blue.html.

Hope this helps.

Scott

4

Hi Scot,
In the scheme you gave me : http://www.hacktronics.com/images/arduino_lcd_connections-lg.jpg
Why and how is the resistor connected to pin 1? what if i use a poteniometer? it seems wierd.

Gnusci,
I would rather have a picture then a sketch of the wiring, i tried the one you gave me but still no luck. its as if the resistor does nothing, and when i upload the code i cant see anything either (after i connect all the data wires)

5

Solved,
the trimmer had to be pulled all the way

6

The resistor (or pot) is to adjust the display contrast. Once you set it with a potentiometer, you can remove the pot and put in a fixed resistor instead.

7

The resistor (or pot) is to adjust the display contrast. Once you set it with a potentiometer, you can remove the pot and put in a fixed resistor instead.

And how would you do that? All of my potentiometers have three terminals but my resistors have only two.

Don

8

floresta:

The resistor (or pot) is to adjust the display contrast. Once you set it with a potentiometer, you can remove the pot and put in a fixed resistor instead.

And how would you do that? All of my potentiometers have three terminals but my resistors have only two.

Don

I guess once you know the right resistence for your lcd screen you dont need 3. I think you connect the resistor between the right lcd pin (pin 3) and the ground. Someone correct me if im wrong.

9

Someone correct me if im wrong.

You are wrong. You should use a voltage divider not a single resistor. Use either a potentiometer or two resistors.

The display may 'work' using your technique, but it will also 'work' if you just connect pin 3 to GND. It will work best with the proper connections.

Don