/*
The analog sensor is connected between pin A0 and pin 4
*/

int row0 = A0;  //first row pin
int row1 = A1;  //first row pin
int row2 = A2;  //first row pin

int col0 = 4;    //first column pin
int col1 = 5;    //first column pin
int col2 = 6;    //first column pin


int incomingValue0 = 0; //variable to save the sensor reading
int incomingValue1 = 0; //variable to save the sensor reading
int incomingValue2 = 0; //variable to save the sensor reading

int incomingValue3 = 0; //variable to save the sensor reading
int incomingValue4 = 0; //variable to save the sensor reading
int incomingValue5 = 0; //variable to save the sensor reading

int incomingValue6 = 0; //variable to save the sensor reading
int incomingValue7 = 0; //variable to save the sensor reading
int incomingValue8 = 0; //variable to save the sensor reading

void setup() {

  // set all rows to INPUT (high impedance):
    pinMode(row0, INPUT_PULLUP);
    pinMode(row1, INPUT_PULLUP);
    pinMode(row2, INPUT_PULLUP);

 //set the firt column as output
  pinMode(col0, OUTPUT);
  pinMode(col1, OUTPUT);
  pinMode(col2, OUTPUT);


  //open serial communication
  Serial.begin(9600);

}

void loop() {

  //set the col0 to low (GND)
  digitalWrite(col0, LOW);
  digitalWrite(col1, HIGH);
  digitalWrite(col2, HIGH);

  //read the three rows pins
    incomingValue0 = analogRead(row0);
    incomingValue1 = analogRead(row1);
    incomingValue2 = analogRead(row2);

  //set the col0 to low (GND)
  digitalWrite(col0, HIGH);
  digitalWrite(col1, LOW);
  digitalWrite(col2, HIGH);

    incomingValue3 = analogRead(row0);
    incomingValue4 = analogRead(row1);
    incomingValue5 = analogRead(row2);

  //set the col0 to low (GND)
  digitalWrite(col0, HIGH);
  digitalWrite(col1, HIGH);
  digitalWrite(col2, LOW);

    incomingValue6 = analogRead(row0);
    incomingValue7 = analogRead(row1);
    incomingValue8 = analogRead(row2);

  // Print the incoming values of the grid:
  
    Serial.print(incomingValue0);
    Serial.print("\t");
    Serial.print(incomingValue1);
    Serial.print("\t");
    Serial.print(incomingValue2);
    Serial.print("\t");
    Serial.print(incomingValue3);
    Serial.print("\t");
    Serial.print(incomingValue4);
    Serial.print("\t");
    Serial.print(incomingValue5);
    Serial.print("\t");
    Serial.print(incomingValue6);
    Serial.print("\t");
    Serial.print(incomingValue7);
    Serial.print("\t");
    Serial.println(incomingValue8);

delay(10); //wait millisecond
}