void setup(){
  pinMode(2, OUTPUT); // digit 1
  pinMode(3, OUTPUT); // top (a)
  pinMode(4, OUTPUT); // top left (f)
  pinMode(5, OUTPUT); // digit 2
  pinMode(6, OUTPUT); // digit 3
  pinMode(7, OUTPUT); // top right (b)
  pinMode(8, OUTPUT); // bottom left (e)
  pinMode(9, OUTPUT); // bottom (d)
  pinMode(10, OUTPUT); // dot
  pinMode(11, OUTPUT); // bottom right (c)
  pinMode(12, OUTPUT); // middle (g)
  pinMode(13, OUTPUT); // digit 4
}

void loop(){
  //digit 1
  digitalWrite(7, LOW); // set b off
  digitalWrite(11, LOW); // set c off
  digitalWrite(4, LOW); // set f off
  digitalWrite(8, LOW); // set e off

  digitalWrite(13, HIGH); // set digit 4 to off
  digitalWrite(6, HIGH); // set digit 3 to off
  digitalWrite(5, HIGH); // set digit 2 to off
  digitalWrite(2, HIGH); // set digit 1 to on

  delay(1);

  //digit 2
  digitalWrite(7, LOW); // set b off
  digitalWrite(11, LOW); // set c off
  digitalWrite(4, LOW); // set f off
  digitalWrite(8, LOW); // set e off

  digitalWrite(13, HIGH); // set digit 4 to off
  digitalWrite(6, HIGH); // set digit 3 to off
  digitalWrite(5, HIGH); // set digit 2 to on
  digitalWrite(2, HIGH); // set digit 1 to off

  delay(1);

  //digit 3
  digitalWrite(7, HIGH); // set b to on
  digitalWrite(11, HIGH); // set c to on
  digitalWrite(4, LOW); // set f off
  digitalWrite(8, LOW); // set e off

  digitalWrite(13, HIGH); // set digit 4 to off
  digitalWrite(6, LOW); // set digit 3 to on
  digitalWrite(5, HIGH); // set digit 2 to off
  digitalWrite(2, HIGH); // set digit 1 to off

  delay(1);

  //digit 4
  digitalWrite(7, LOW); // set b off
  digitalWrite(11, LOW); // set c off
  digitalWrite(4, HIGH); // set f on
  digitalWrite(8, HIGH); // set e on

  digitalWrite(13, LOW); // set digit 4 to on
  digitalWrite(6, HIGH); // set digit 3 to off
  digitalWrite(5, HIGH); // set digit 2 to off
  digitalWrite(2, HIGH); // set digit 1 to off

  delay(1);
}