/*
Arduino | hardware-help
Keypad calculator
Zeruxe — 6/16/24 at 7:25 PM
From this not-so-good example:
https://www.hackster.io/nolimitcircuit/arduinolator-an-arduino-calculator-b544ff
*/
#include <Keypad.h>
#include <LiquidCrystal.h>
const byte ROWS = 4;
const byte COLS = 4;
const char keys [ROWS] [COLS] = {
{'1', '2', '3', '+'},
{'4', '5', '6', '-'},
{'7', '8', '9', '*'},
{'C', '0', '=', '/'}
};
const byte rowPins[ROWS] = {23, 25, 27, 29};
const byte colPins[COLS] = {31, 33, 35, 37};
Keypad myKeypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
LiquidCrystal lcd(12, 11, 10, 9, 8, 7);
boolean presentValue = false;
boolean next = false;
boolean final = false;
String num1, num2;
int answer;
char op;
void setup()
{
Serial.begin(9600);
lcd.begin(16, 2); //LCD starts
lcd.setCursor(0, 0);
lcd.print("An Arduino"); //All this is text. You can edit it
lcd.setCursor(0, 1);
lcd.print("Calculator");
delay(3000);
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("The");
lcd.setCursor(0, 1);
lcd.print("Arduinolator!");
delay(3000);
lcd.clear(); //LCD clears, and you can begin using it.
}
void loop() {
char key = myKeypad.getKey();
if (key != NO_KEY && (key == '1' || key == '2' || key == '3' || key == '4' || key == '5' || key == '6' || key == '7' || key == '8' || key == '9' || key == '0'))
{
if (presentValue != true)
{
num1 = num1 + key;
int numLength = num1.length();
lcd.setCursor(15 - numLength, 0); //to adjust one whitespace for operator
lcd.print(num1);
}
else
{
num2 = num2 + key;
int numLength = num2.length();
lcd.setCursor(15 - numLength, 1);
lcd.print(num2);
final = true;
}
}
else if (presentValue == false && key != NO_KEY && (key == '/' || key == '*' || key == '-' || key == '+'))
{
if (presentValue == false)
{
presentValue = true;
op = key;
lcd.setCursor(15, 0);
lcd.print(op);
}
}
else if (final == true && key != NO_KEY && key == '=') {
Serial.println("Equal pressed");
if (op == '+') {
answer = num1.toInt() + num2.toInt();
}
else if (op == '-') {
answer = num1.toInt() - num2.toInt();
}
else if (op == '*') {
answer = num1.toInt() * num2.toInt();
}
else if (op == '/') {
answer = num1.toInt() / num2.toInt();
}
lcd.clear();
//lcd.setCursor(0, 0);
lcd.setCursor(15, 0);
//lcd.autoscroll();
lcd.print(answer);
//lcd.noAutoscroll();
}
else if (key != NO_KEY && key == 'C') {
lcd.clear();
presentValue = false;
final = false;
num1 = "";
num2 = "";
answer = 0;
op = ' ';
}
}