/* Digit table for the 7-segment display */
const uint8_t digitTable[] = {
  0b11000000,
  0b11111001,
  0b10100100,
  0b10110000,
  0b10011001,
  0b10010010,
  0b10000010,
  0b11111000,
  0b10000000,
  0b10010000,
};

int btnUP = A0;
int btnDOWN = A1;

// bits for the 7-segment
int bits[7] = {0};
int value = 0;


void setup() {
  // set up all 7-segment
  for(short int i=0; i < 7;i++){
    pinMode(i, OUTPUT);
  }

  pinMode(btnUP, INPUT_PULLUP);
  pinMode(btnDOWN, INPUT_PULLUP);

  extractByte(digitTable[value],bits);
  write7seg(bits);

}

void loop() {

  if(digitalRead(btnUP) == LOW){
    if(value < 9){
      value++; 
    }
    delay(200);
  }
  if(digitalRead(btnDOWN) == LOW){
    if(value > 0){
      value--;
    }
    delay(200);
  }
  extractByte(digitTable[value],bits);
  write7seg(bits);
 
}

void write7seg(int *bits){
  for(short int i=0; i < 7;i++){
    digitalWrite(i, bits[i]);
  }
}

void extractByte (unsigned char Byte, int *bits) {
  for (short int i = 0; i < 7; i++) {
    bits[i] = (Byte >> i) & 0x01;
  }
}