#define hex_2_0  0  // GP 0
#define hex_2_1  1  // GP 1
#define hex_2_2  2  // GP 2
#define hex_2_3  3  // GP 3
#define hex_2_4  4  // GP 4
#define hex_2_5  5  // GP 5
#define hex_2_6  6  // GP 6
#define hex_2_7  7  // GP 7

uint8_t count = 0; 

void setup() {
  Serial.begin(9600);

  pinMode(hex_2_0, OUTPUT);   // 1
  pinMode(hex_2_1, OUTPUT);   // 2
  pinMode(hex_2_2, OUTPUT);   // 4
  pinMode(hex_2_3, OUTPUT);   // 8
  pinMode(hex_2_4, OUTPUT);   // 16
  pinMode(hex_2_5, OUTPUT);   // 32
  pinMode(hex_2_6, OUTPUT);   // 64
  pinMode(hex_2_7, OUTPUT);   // 128

  // initialize inputs to Low
  digitalWrite(hex_2_0, LOW);
  digitalWrite(hex_2_1, LOW);
  digitalWrite(hex_2_2, LOW);
  digitalWrite(hex_2_3, LOW);
  digitalWrite(hex_2_4, LOW);
  digitalWrite(hex_2_5, LOW);
  digitalWrite(hex_2_6, LOW);
  digitalWrite(hex_2_7, LOW);
}

void loop() {
 
 while(1)
 {
    Serial.println(count);

    if((count % 2) > 0) { digitalWrite(hex_2_0, HIGH); } else { digitalWrite(hex_2_0, LOW); }

    if((count % 4) > 1) { digitalWrite(hex_2_1, HIGH); } else { digitalWrite(hex_2_1, LOW); }

    if((count % 8) > 3) { digitalWrite(hex_2_2, HIGH); } else { digitalWrite(hex_2_2, LOW); }

    if((count % 16) > 7) { digitalWrite(hex_2_3, HIGH); } else { digitalWrite(hex_2_3, LOW); }

    if((count % 32) > 15) { digitalWrite(hex_2_4, HIGH); } else { digitalWrite(hex_2_4, LOW); }

    if((count % 64) > 31) { digitalWrite(hex_2_5, HIGH); } else { digitalWrite(hex_2_5, LOW); }

    if((count % 128) > 63) { digitalWrite(hex_2_6, HIGH); } else { digitalWrite(hex_2_6, LOW); }

    if((count % 256) > 127) { digitalWrite(hex_2_7, HIGH); } else { digitalWrite(hex_2_7, LOW); }

    if(count < 0xFF) count++;
     else exit(1);
     
    delay(10);
 }
 exit(1); 
}