int col1 = 12, col2 = 11, col3 =10;
int colPins[3] = {col1, col2, col3};
int row1 = 9, row2 = 8, row3 = 7;
int rowPins[3] = {row1, row2, row3};
int matrix[3][3] = {
  {0, 1, 0},
  {1, 0, 1},
  {0, 1, 0}
};

void init_led_matrix() {
 
  for(int col = 0; col < 3; col++) {
    pinMode(colPins[col], OUTPUT);
    digitalWrite(colPins[col], 1);
  }
  for(int row = 0; row < 3; row++) {
    pinMode(rowPins[row], OUTPUT);
    digitalWrite(rowPins[row], 0);
  }


}

void refresh_led_matrix() {
  for(int row = 0; row < 3; row++) {
    for(int col = 0; col < 3; col++) {
      digitalWrite(colPins[col], !matrix[row][col]);
    }
    digitalWrite(rowPins[row], 1);
    digitalWrite(rowPins[row], 0);
  }

}

void setup() {
  // put your setup code here, to run once:
  init_led_matrix();
}

unsigned long lastRefreshed = 0;
#define REFRESH_PERIOD 16 // ms

void loop() {
  // put your main code here, to run repeatedly:
  if(millis() >= lastRefreshed + REFRESH_PERIOD) {
    lastRefreshed = millis();
    refresh_led_matrix();
  }
}