void setup() {
  for (int pin = 2; pin <= 9; pin++) {
    pinMode(pin, OUTPUT);
  }
}

void loop() {

  digitalWrite(9, HIGH);
  delay(5);
  digitalWrite(9, LOW);
  delay(5);

  show9(); delay(1000);
  show8(); delay(1000);
  show7(); delay(1000);
  show6(); delay(1000);
  show5(); delay(1000);
  show4(); delay(1000);
  show3(); delay(1000);
  show2(); delay(1000);
  show1(); delay(1000);
  show0(); delay(1000);
}

// Define each digit manually
void show0() {
  writeSegments(1,1,1,1,1,1,0);
}
void show1() {
  writeSegments(0,1,1,0,0,0,0);
}
void show2() {
  writeSegments(1,1,0,1,1,0,1);
}
void show3() {
  writeSegments(1,1,1,1,0,0,1);
}
void show4() {
  writeSegments(0,1,1,0,0,1,1);
}
void show5() {
  writeSegments(1,0,1,1,0,1,1);
}
void show6() {
  writeSegments(1,0,1,1,1,1,1);
}
void show7() {
  writeSegments(1,1,1,0,0,0,0);
}
void show8() {
  writeSegments(1,1,1,1,1,1,1);
}
void show9() {
  writeSegments(1,1,1,1,0,1,1);
}

// Function to write each segment
void writeSegments(bool a, bool b, bool c, bool d, bool e, bool f, bool g) {
  digitalWrite(2, a); // A
  digitalWrite(3, b); // B
  digitalWrite(4, c); // C
  digitalWrite(5, d); // D
  digitalWrite(6, e); // E
  digitalWrite(7, f); // F
  digitalWrite(8, g); // G
}