#include <Keypad.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

const int SCREEN_WIDTH = 128; // OLED display width, in pixels
const int SCREEN_HEIGHT = 64; // OLED display height, in pixels


const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 }; // Pins
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
// Declaration for an SSD1306 display 
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);


void setup() {
  Serial.begin(9600);
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    while(true);
  }
}

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


  if (key != NO_KEY) {
    Serial.println(key);

    display.clearDisplay();

    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.setCursor(0, 10);
    // Display static text
    display.println(key);
    display.display();
  }

  delay(100);
}