#include <LiquidCrystal.h>
#include <Keypad.h>
#define PUSH_BUTTON_PIN 6
const byte KEYPAD_ROWS = 4;
const byte KEYPAD_COLS = 4;
byte rowPins[KEYPAD_ROWS] = {5, 4, 3, 2};
byte colPins[KEYPAD_COLS] = {A3, A2, A1, A0};
char keys[KEYPAD_ROWS][KEYPAD_COLS] = {
{'1', '2', '3', '+'},
{'4', '5', '6', '-'},
{'7', '8', '9', '*'},
{'.', '0', '=', '^'}
};
uint64_t value = 0;
LiquidCrystal lcd(12, 11, 10, 9, 8, 7);
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, KEYPAD_ROWS, KEYPAD_COLS);
void showSplashScreen() {
lcd.print("Loading...");
lcd.setCursor(0, 1);
lcd.print("\x5B");
lcd.setCursor(1, 2);
for (byte i = 1; i < 19; i++) {
lcd.print("\xFF");
delay(100);
}
lcd.print("\x5D");
delay(350);
lcd.clear();
}
void setup() {
Serial.begin(115200);
pinMode(PUSH_BUTTON_PIN, INPUT_PULLUP);
pinMode(A5, INPUT);
pinMode(A4, OUTPUT);
lcd.begin(16, 2);
showSplashScreen();
lcd.setCursor(2, 0);
}
char operation = 0;
String memory = "";
String current = "";
uint64_t currentDecimal;
bool decimalPoint = false;
double calculate(char operation, double left, double right) {
switch (operation) {
case '+': return left + right;
case '-': return left - right;
case '*': return left * right;
// case '/': return left / right;
case '^': return pow((float)left, (float)right);
/* refer here:
https://www.arduino.cc/reference/en/language/functions/math/pow/
for the (float) cast
*/
}
}
void processInput(char key) {
if ('-' == key && current == "") {
current = "-";
lcd.print("-");
return;
}
switch (key) {
case '+':
case '-':
case '*':
// case '/':
case '^':
if (!operation) {
memory = current;
current = "";
}
operation = key;
lcd.setCursor(0, 1);
lcd.print(key);
lcd.setCursor(current.length() + 1, 1);
return;
case '=':
float leftNum = memory.toDouble();
float rightNum = current.toDouble();
memory = String(calculate(operation, leftNum, rightNum));
current = "";
lcd.clear();
lcd.setCursor(1, 0);
lcd.print(memory);
lcd.setCursor(0, 1);
lcd.print(operation);
return;
}
if ('.' == key && current.indexOf('.') >= 0) {
return;
}
if ('.' != key && current == "0") {
current = String(key);
} else if (key) {
current += String(key);
}
lcd.print(key);
}
void loop() {
if (digitalRead(PUSH_BUTTON_PIN) == LOW) {
lcd.display();
lcd.blink();
analogWrite(A4, analogRead(A5));
char key = keypad.getKey();
if (key != NO_KEY) {
processInput(key);
}
} else {
lcd.noBlink();
lcd.clear();
lcd.noDisplay();
}
}