void setup() {
  // put your setup code here, to run once:
  volatile char *outF, *inK, *outA,*outC;
  volatile char *dirF, *dirK, *dirA, *dirC;
  outF=0x31;inK=0x106;outA=0x22;outC=0x28; // Address initialization
  dirF=0x30;dirK=0x107;dirA=0x21;dirC=0x27; // Direction Initialization
  
  *dirF=0x0F;*dirK=0x00;*dirA=0x0F;*dirC=0x0F;
  while(1){
    for(int i=0;i<4;i++){
      *outF=1<<i; // output column connection 
      *outA=*inK; // read the input value, ROW identification
      if(*inK !=0){
        *outC=1<<i; // Column Identification
        for(volatile long j=0;j<200000;j++); //Delay
        *outC=0x00;
      }
    }
  }

//Blue LED - coloumn and Yellow LED - Row
}

void loop() {
  // put your main code here, to run repeatedly:

}