#include <Keypad.h>

const byte rowNum = 4;
const byte colNum = 4;
const byte controlPin = 10;

void dot(void);

char pad[rowNum][colNum] = {
  { 'A', 'B', 'C', 'D'},
  { 'E', 'F', 'G', 'H'},
  { 'I', 'J', 'K', 'L'},
  { 'M', 'N', 'O', 'P'}
};

byte pinRow[rowNum] = {9, 8, 7, 6};
byte pinCol[colNum] = {5, 4, 3, 2};

Keypad keypad = Keypad(makeKeymap(pad), pinRow, 
pinCol, rowNum, colNum);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(10, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  char key = keypad.getKey();

  switch (key) {
    case 'F':
      dot();
      dot();
      dash();
      dot();
      delay(50);
      break;
    case 'G':
      delay(50);
      break;
  }
}

void dot(void) {
  digitalWrite(controlPin, HIGH);
  delay(100);
  digitalWrite(controlPin, LOW);
  delay(50);
}

void dash(void) {
  digitalWrite(controlPin, HIGH);
  delay(300);
  digitalWrite(controlPin, LOW);
  delay(50);
}