// C++ code
//

// 初始接腳
int rows[]={18,5,17,16};
int cols[]={4,0,2,15};
int row=4;
int col=4;
int i,x,y;
char tbl[]={'1','2','3','A',
                 '4','5','6','B',
                 '7','8','9','C',
                  '*','0','#','D'};
/*
x,y 00 '1'
x,y 10 '4'
x,y 23 'C'
x,y 33 'D'
*/

void setup()
{
  Serial.begin(9600);
  for (i=0;i<row;i++)
    pinMode(rows[i], OUTPUT);
  for (i=0;i<col;i++)
    pinMode(cols[i], INPUT_PULLUP);

}

bool now,old=false;
void loop()
{
  now=scan();
  if (now==true && old==false){
    Serial.print(x);
    Serial.print(",");
    Serial.print(y);
    Serial.print("=>");
    Serial.println(tbl[x*4+y]);
  }
  old=now;
  
}

bool scan(){
   //scan row[0]
  
  x=0;
  digitalWrite(rows[0],LOW);
  digitalWrite(rows[1],HIGH);
  digitalWrite(rows[2],HIGH);
  digitalWrite(rows[3],HIGH);
  for (i=0;i<col;i++)
    if (digitalRead(cols[i])==0){
        y=i;
    return true;
  }
  //scan row[1]
  x=1;
  digitalWrite(rows[0],HIGH);
  digitalWrite(rows[1],LOW);
  digitalWrite(rows[2],HIGH);
  digitalWrite(rows[3],HIGH);
  for (i=0;i<col;i++)
    if (digitalRead(cols[i])==0){
        y=i;
    return true;
  }
  //scan row[2]
  x=2;
  digitalWrite(rows[0],HIGH);
  digitalWrite(rows[1],HIGH);
  digitalWrite(rows[2],LOW);
  digitalWrite(rows[3],HIGH);
  for (i=0;i<col;i++)
    if (digitalRead(cols[i])==0){
        y=i;
    return true;
  }
   //scan row[3]
  x=3;
  digitalWrite(rows[0],HIGH);
  digitalWrite(rows[1],HIGH);
  digitalWrite(rows[2],HIGH);
  digitalWrite(rows[3],LOW);
  for (i=0;i<col;i++)
    if (digitalRead(cols[i])==0){
        y=i;
    return true;
  }
 return false;
}