A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers.

Liquid crystals do not emit light directly, instead using a backlight or reflector to produce images in color or monochrome.

LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden, such as preset words, digits, and seven-segment displays, as in a digital clock.

They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements.

LCD 1602 Keyboard Shield


This is a simple example of a LCD 16 character 2 line (1602) shield that mounts directly on an Uno or Mega.

This also has an addition benefit of 5 built in buttons with built in series resistors that all use the A0 input.

The buttons use a series of resistors that act as voltage dividers giving each button a unique voltage.

Since resistors do vary, you will need to run the program (Keys_1602shield) to set the voltage ranges.

In serial monitor, you will see the key and the bit integer value.

Write down these values.

In the program, set the break values between these measurements.

NOTE: this LCD shield wiring differs from some LCDs with the code:

LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

Then run the LCD_KS_Menu program for a simple menu example.

Use the UP/Down to scroll the menu items.

Use the RIGHT button to set the Digital ouput.

Use the LEFT button to return to the menu and turn the output off.


Arduino 20x4 LCD Module IIC I2C Interface


Here is a quick simple example for hooking up an LCD to an Arduino.

There are lots of LCD options , but $21/2 with I2C attached was too good to pass up !

This specific example uses:

Arduino Uno R3 $16

SunFounder 2004 20x4 LCD Module IIC I2C Interface Adapter Blue Backlight for Raspberry Arduino UNO R3 MEGA2560 $21 per 2


(NOTE: I2C connector module is attached and include with this LCD ! )

The blue potentiometer on the I2C LCD1602 (see the figure below) is used to adjust the backlight  for better display.

Also MEGA compatible with much more memory 256K vs Uno 32K

Video instruction

Electrical Connections: ( 4 wires same for most I2C Adapters )

LCD                      UNO

GND                      Pin GND

VCC                      Pin 5V

SDA                      Pin A4

SCL                      Pin A5


First you need to download the Sunfounder LCD zip at:


Install the zip file into Arduino IDE:

Sketch > Include Library > Add .ZIP Library

Check “includes library” menu after installing.

I2C LCD2004


Here are some helpful tutorials on some the systems available with Scada123 to try on your own.

You can view videos at:     Youtube Channel Scada LLC

Sort through Topics on the left Menu "Tutorial Menu"

Click on one the Topic Tags that interest you.

License : All programs in the tutorial section are free software. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful,  but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.