#include <LiquidCrystal.h>
#include <Keypad.h>

// LCD pin setup (PA8=RS, PA9=EN, PA10= D4, PA11=D5, PA12=D6, PA15=D7)
LiquidCrystal lcd(PA8, PA9, PA10, PA11, PA12, PA15);

// Keypad setup
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns

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

// Connect keypad rows to PB12, PB13, PB14, PB15
byte rowPins[ROWS] = {PB12, PB13, PB14, PB15}; 
// Connect keypad cols to PB8, PB9, PB10, PB11
byte colPins[COLS] = {PB8, PB9, PB10, PB11}; 

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

void setup() {
  lcd.begin(16, 2); // initialize LCD
  lcd.print("STM32 Keypad");
  delay(2000);
  lcd.clear();
  lcd.print("Press a key:");
}

void loop() {
  char key = keypad.getKey();

  if (key) { // If a key is pressed
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Key Pressed:");
    lcd.setCursor(0, 1);
    lcd.print(key);
  }
}