Arduino - Keypad - LCD

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×LCD I2C
1×Keypad 3x4
1×Keypad 4x4 (optional)
1×Breadboard
4×Jumper Wires
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About Keypad and LCD

If you do not know about keypad and LCD (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino Keypad LCD Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Arduino Code

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-keypad-lcd */ #include <Keypad.h> #include <LiquidCrystal_I2C.h> const int ROW_NUM = 4; //four rows const int COLUMN_NUM = 3; //three columns char keys[ROW_NUM][COLUMN_NUM] = { {'1','2','3'}, {'4','5','6'}, {'7','8','9'}, {'*','0','#'} }; byte pin_rows[ROW_NUM] = {9, 8, 7, 6}; //connect to the row pinouts of the keypad byte pin_column[COLUMN_NUM] = {5, 4, 3}; //connect to the column pinouts of the keypad Keypad keypad = Keypad(makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM ); LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows int cursorColumn = 0; void setup(){ lcd.init(); // initialize the lcd lcd.backlight(); } void loop(){ char key = keypad.getKey(); if (key) { lcd.setCursor(cursorColumn, 0); // move cursor to (cursorColumn, 0) lcd.print(key); // print key at (cursorColumn, 0) cursorColumn++; // move cursor to next position if(cursorColumn == 16) { // if reaching limit, clear LCD lcd.clear(); cursorColumn = 0; } } }

Quick Steps

  • Connect Arduino to PC via USB cable
  • Open Arduino IDE, select the right board and port

On Arduino IDE, Go to Tool Manage Libraries

Arduino add library
  • Search “keypad”, then find the keypad library by Mark Stanley, Alexander Brevig
  • Click Install button to install keypad library.
  • Arduino keypad library
  • Search “LiquidCrystal I2C”, then find the LiquidCrystal_I2C library by Frank de Brabander
  • Click Install button to install LiquidCrystal_I2C library.
  • Arduino LiquidCrystal I2C library
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Arduino IDE Upload Code
  • Press some keys on keypad
  • See the result in LCD

If LCD displays nothing, see Troubleshooting on LCD I2C

Code Explanation

Read the line-by-line explanation in comment lines of source code!

Video Tutorial

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Keypad and LCD on Commercial Products

  • Casio fx-115ES PLUS Engineering/Scientific Calculator
  • Yale Security Assure Lock
  • Digital Multimeter
  • Nest 3rd Generation Thermostat

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