const int jmlBaris=4;
const int jmlKolom=3;
const int bouncing=20; //timer 20ms
const char keymap[jmlBaris][jmlKolom] = {
 {'1','2','3'},
 {'4','5','6'},
 {'7','8','9'},
 {'*','0','#'} };
const int pinBaris[jmlBaris]={5,4,3,2};
const int pinKolom[jmlKolom]={6,7,8};

void setup() {
 // put your setup code here, to run once:
Serial.begin(9600);
Serial.println("PERCOBAAN KEYPAD");

for(int baris=0;baris<jmlBaris;baris++)
  {
  pinMode(pinBaris[baris],INPUT);
  digitalWrite(pinBaris[baris],HIGH);
  }
for(int kolom=0;kolom<jmlKolom;kolom++)
  {
  pinMode(pinKolom[kolom],OUTPUT);
  digitalWrite(pinKolom[kolom],HIGH);
  }
}

void loop() {
char key = getKey();
if (key !=0)
  {
  Serial.print("tombol yang ditekan : ");
  Serial.println(key);
  }
}

char getKey() {
 char key=0; //tidakk ada yang ditekan
 for(int kolom=0;kolom<jmlKolom;kolom++)
  {
  digitalWrite(pinKolom[kolom],LOW);
  for(int baris=0;baris<jmlBaris;baris++)
    {
    if(digitalRead(pinBaris[baris])==LOW)
      {
      delay(bouncing);
      while(digitalRead(pinBaris[baris])==LOW)
      key = keymap[baris][kolom];
      }
    }
 digitalWrite(pinKolom[kolom],HIGH);
 }
 return key;
}