#include <LiquidCrystal.h> 
const int Rs = 13, En = 12, D4 = 11, D5 = 10, D6 = 9, D7 = 8; 
LiquidCrystal lcd(Rs, En, D4, D5, D6, D7); 
char button;

void setup() {
  lcd.begin(16, 2); 
  lcd.setCursor(0, 0); 
  lcd.print("TEST BUTTON");
  lcd.setCursor(12, 0); 
  lcd.print("=");
  pinMode(0, OUTPUT); 
  pinMode(1, OUTPUT); 
  pinMode(2, OUTPUT); 
  pinMode(3, OUTPUT); 
  pinMode(4, INPUT_PULLUP); 
  pinMode(5, INPUT_PULLUP);
  pinMode(6, INPUT_PULLUP); 
  pinMode(7, INPUT_PULLUP);
}

void loop() {
  button=' '; 
  digitalWrite(3, LOW); 
  digitalWrite(2, HIGH); 
  digitalWrite(1, HIGH); 
  digitalWrite(0, HIGH); 
  if (digitalRead(7) == LOW)button = '1'; 
  if (digitalRead(6) == LOW)button = '4'; 
  if (digitalRead(5) == LOW)button = '7'; 
  if (digitalRead(4) == LOW)button = '*'; 
  digitalWrite(3, HIGH); 
  digitalWrite(2, LOW); 
  digitalWrite(1, HIGH); 
  digitalWrite(0, HIGH); 
  if (digitalRead(7) == LOW)button = '2'; 
  if (digitalRead(6) == LOW)button = '5'; 
  if (digitalRead(5) == LOW)button = '8'; 
  if (digitalRead(4) == LOW)button = '0'; 
  digitalWrite(3, HIGH); 
  digitalWrite(2, HIGH); 
  digitalWrite(1, LOW); 
  digitalWrite(0, HIGH); 
  if (digitalRead(7) == LOW)button = '3'; 
  if (digitalRead(6) == LOW)button = '6'; 
  if (digitalRead(5) == LOW)button = '9'; 
  if (digitalRead(4) == LOW)button = '#'; 
   digitalWrite(3, HIGH); 
  digitalWrite(2, HIGH); 
  digitalWrite(1, HIGH); 
  digitalWrite(0, LOW); 
  if (digitalRead(7) == LOW)button = 'A'; 
  if (digitalRead(6) == LOW)button = 'B'; 
  if (digitalRead(4) == LOW)button = 'D'; 
  if (digitalRead(5) == LOW) {

    lcd.setCursor(14, 0); 
    lcd.print("   ");
  }
  if (button != ' ') {
    lcd.setCursor(14, 0); 
    lcd.print(button); 
    button = ' '; 
  }
}