//original code from :https://www.youtube.com/watch?v=ycV1cP_anvI

#include<stdio.h>
#include<stdlib.h>

//byte row_val = b000000001;
char key_val;
char *key_val_2;

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


void row_selection(char *key_select);
char keySelect(int row, byte col);
int char_To_int(const char *str);

void setup() {
  
  DDRB |= 0x0F; // 4 ultimos bits del puerto B como salida 00001111 last 4 bit of PORTB as output 00001111 (se usa el MSB desde el bit 0 al bit 3 )
  DDRC |= 0xF0; // 4 ultimos bits del puerto C como entrada 11110000
  Serial.begin(9600);
}

void loop() {
 
  
 row_selection(&key_val);
  //*key_val_2 = key_val;
  //Serial.print(key_val);
  //const char *str = key_val;
  //char_To_int(str);

/*
PORTB |= 0x0F;
Serial.println(PORTB,BIN);
delay(1000);
PORTB &= 0x00;
//PORTB |= 0x0F;
Serial.println(PORTB,BIN);
delay(1000);
*/
}

int char_To_int(const char *str){
  //const char *str = "12345";
  int x;
  sscanf(str, "%d", &x);
  Serial.println(x,BIN);
 return x;
}

void row_selection(char *key_select){
 
  for(int i=0; i<4; i++){
    
    //Serial.print("pinc ");   
    //Serial.println(PINC);
    
    PORTB &= 0x00;
    PORTB |= ( 1 << i );
    /*Serial.print("portB ");    
    Serial.println(PORTB,BIN);*/
    //Serial.println(PINC);
    if((PINC & 0x0F)>=1){
      
      delay(10);
      //Serial.println("key press " );
      //Serial.println(PINC);
       *key_select = keySelect(i,PINC);
       char_To_int(key_select);
      Serial.print("key  "); 
      Serial.println(*key_select);
      
      while((PINC&0x0F)>=1){
        //Serial.println("inside while");
        if((PINC == 0)){
          return;
        }
      }
      //return key_select ;
    }
    
    //delay(10);
  }
 // return key_select ;
}

char keySelect(int row, byte col){
  char key_Val ;
  switch(col){

    case 1:
      //Serial.println((key[row][0]));
      key_Val= key[row][0];
      
      break;

    case 2:
      //Serial.println(key[row][1]);
      key_Val = key[row][1];
      break;

    case 4:
      //Serial.println(key[row][2]);
      key_Val = key[row][2];
      break;

    case 8:
     // Serial.println(key[row][3]);
      key_Val = key[row][3];
      break;

    default:
      //return ;
      break;
  }
  return key_Val;
}