Arduino Tutorial

By LiterallyTheOne

3: LCD and Keypad

Introduction

• Previous tutorial: 7-segment
• This tutorial: LCD and Keypad

LCD

LCD Arduino SimulIDE

• RS: 12
• RW: ground
• E: 11
• D4: 5
• D6: 4
• D7: 3
• D8: 2

Liquid Crystal

• Well-known package
• Work with LCD

Add Liquid Crystal to PlatformIO

• In platfromio.ini

lib_deps =
  arduino-libraries/LiquidCrystal

• in main.cpp

#include <LiquidCrystal.h>

Make an LCD Object

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

begin

• initilizes the LCD

lcd.begin(cols, rows);

• Example:

lcd.begin(16, 2);

Write

• Write a character

lcd.write(ch);

• Example:

lcd.write('h');

Print

• Write a text

lcd.print(text);

• Example:

lcd.print("Hello World!");

Set Cursor

• Jumps to the given column and row

lcd.setCursor(col, row);

• Example:

lcd.setCursor(5, 1);

Clear

• Clears the LCD and jumps to the start

lcd.clear();

• Example:

lcd.clear();

LCD Hello World

• 1st row, 3rd column: "Hello"
• 2nd row, 4th column: "World"

Keypad

• A series of keys
• in a matrix

Connect the Keypad

• row-0: 0
• row-1: 1
• row-2: 6
• row-3: 7
• col-0: 8
• col-1: 9
• col-2: 10

Add Keypad to PlatformIO

• in platformio.ini

lib_deps =
  ...
  Keypad

• in main.cpp

#include <Keypad.h>

Define Keys

const byte ROWS = 4;
const byte COLS = 3;

char keys[ROWS][COLS] = {
    {'1', '2', '3'},
    {'4', '5', '6'},
    {'7', '8', '9'},
    {'*', '0', '#'}};

Define pins

byte rowPins[ROWS] = {0, 1, 6, 7};
byte colPins[COLS] = {8, 9, 10};

Make a keypad Object

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

Get Key

• Gets the pressed key

keypad.getKey();

• Example:

char key = keypad.getKey();

Keypad to LCD

Login System

• Correct username: 12
• Correct password: 5662
• Enter: #

Link to the tutorial and materials