#define FIRST_SEGMENT_PIN 2
#define SEGMENT_COUNT 7
byte numberSegments[10] = { 
  0b00111111, 0b00001010, 0b01011101, 0b01011110, 0b01101010, 
  0b01110110, 0b01110111, 0b00011010, 0b01111111, 0b01111110,
};
void setup ()
{
 for (int i = 0; i < SEGMENT_COUNT; ++i) 
 pinMode(i + FIRST_SEGMENT_PIN, OUTPUT);
}
void loop ()
{
 int number = (millis() / 1000) % 10;
 int mask = numberSegments[number];
for (int i = 0; i < SEGMENT_COUNT; ++i) {
   boolean enableSegment = bitRead (mask, i);
  digitalWrite(i + FIRST_SEGMENT_PIN, enableSegment);
  }
}