I am currently programming a calculator using an Arduino Uno Board, but for some reason the LCD does not display anything, I have looked online and some have said to change the contrast on the back of the LCD but that doesn't work either.
One thing i noticed was that at one point the L light on the Arduino Uno Board was flashing everytime I pressed a +,-,x,÷ key.
Here is the code I used:
/*
Arduino Keypad calculator Program
*/
#include <LiquidCrystal_I2C.h> //Header file for LCD from https://www.arduino.cc/en/Reference/LiquidCrystal
#include <Keypad.h> //Header file for Keypad from https://github.com/Chris--A/Keypad
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Three columns
// Define the Keymap
char keys[ROWS][COLS] = {
{'7', '8', '9', 'D'},
{'4', '5', '6', 'C'},
{'1', '2', '3', 'B'},
{'*', '0', '#', 'A'}
};
byte rowPins[ROWS] = { 0, 1, 2, 3 };// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte colPins[COLS] = { 4, 5, 6, 7 }; // Connect keypad COL0, COL1 and COL2 to these Arduino pins.
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS ); // Create the Keypad
const int rs = 8, en = 9, d4 = 10, d5 = 11, d6 = 12, d7 = 13; //Pins to which LCD is connected
LiquidCrystal_I2C lcd(0x27, 16, 2);
long Num1, Num2, Number;
char key, action;
boolean result = false;
void setup() {
lcd.begin(16, 2); //We are using a 16*2 LCD display
lcd.print("Arduino Calculator"); //Display a intro message
lcd.setCursor(0, 1); // set the cursor to column 0, line 1
lcd.print("-YEEYEE"); //Display a intro message
delay(2000); //Wait for display to show info
lcd.clear(); //Then clean it
}
void loop() {
key = kpd.getKey(); //storing pressed key value in a char
if (key != NO_KEY)
DetectButtons();
if (result == true)
CalculateResult();
DisplayResult();
}
void DetectButtons()
{
lcd.clear(); //Then clean it
if (key == '*') //If cancel Button is pressed
{
Serial.println ("Button Cancel");
Number = Num1 = Num2 = 0;
result = false;
}
if (key == '1') //If Button 1 is pressed
{ Serial.println ("Button 1");
if (Number == 0)
Number = 1;
else
Number = (Number * 10) + 1; //Pressed twice
}
if (key == '4') //If Button 4 is pressed
{ Serial.println ("Button 4");
if (Number == 0)
Number = 4;
else
Number = (Number * 10) + 4; //Pressed twice
}
if (key == '7') //If Button 7 is pressed
{ Serial.println ("Button 7");
if (Number == 0)
Number = 7;
else
Number = (Number * 10) + 7; //Pressed twice
}
if (key == '0')
{ Serial.println ("Button 0"); //Button 0 is Pressed
if (Number == 0)
Number = 0;
else
Number = (Number * 10) + 0; //Pressed twice
}
if (key == '2') //Button 2 is Pressed
{ Serial.println ("Button 2");
if (Number == 0)
Number = 2;
else
Number = (Number * 10) + 2; //Pressed twice
}
if (key == '5')
{ Serial.println ("Button 5");
if (Number == 0)
Number = 5;
else
Number = (Number * 10) + 5; //Pressed twice
}
if (key == '8')
{ Serial.println ("Button 8");
if (Number == 0)
Number = 8;
else
Number = (Number * 10) + 8; //Pressed twice
}
if (key == '#')
{ Serial.println ("Button Equal");
Num2 = Number;
result = true;
}
if (key == '3')
{ Serial.println ("Button 3");
if (Number == 0)
Number = 3;
else
Number = (Number * 10) + 3; //Pressed twice
}
if (key == '6')
{ Serial.println ("Button 6");
if (Number == 0)
Number = 6;
else
Number = (Number * 10) + 6; //Pressed twice
}
if (key == '9')
{ Serial.println ("Button 9");
if (Number == 0)
Number = 9;
else
Number = (Number * 10) + 9; //Pressed twice
}
if (key == 'A' || key == 'B' || key == 'C' || key == 'D') //Detecting Buttons on Column 4
{
Num1 = Number;
Number = 0;
if (key == 'A')
{
Serial.println ("Addition");
action = '+';
}
if (key == 'B')
{
Serial.println ("Subtraction");
action = '-';
}
if (key == 'C')
{
Serial.println ("Multiplication");
action = '*';
}
if (key == 'D')
{
Serial.println ("Division");
action = '/';
}
delay(100);
}
}
void CalculateResult()
{
if (action == '+')
Number = Num1 + Num2;
if (action == '-')
Number = Num1 - Num2;
if (action == '*')
Number = Num1 * Num2;
if (action == '/')
Number = Num1 / Num2;
}
void DisplayResult()
{
lcd.setCursor(0, 0); // set the cursor to column 0, line 1
lcd.print(Num1); lcd.print(action); lcd.print(Num2);
if (result == true)
{
lcd.print(" ="); //Display the result
lcd.print(Number);
}
lcd.setCursor(0, 1); // set the cursor to column 0, line 1
lcd.print(Number); //Display the result
}
