TrafficSignal.ino

byte seven_seg_digits[10] = { B11111100,  // = 0
                              B01100000,  // = 1
                              B11011010,  // = 2
                              B11110010,  // = 3
                              B01100110,  // = 4
                              B10110110,  // = 5
                              B10111110,  // = 6
                              B11100000,  // = 7
                              B11111110,  // = 8
                              B11100110   // = 9
                             }; 
// connect to the ST_CP of 74HC595 (pin 3,latch pin, pin 5 of IC)
int latchPin = 3;//12; //3;
// connect to the SH_CP of 74HC595 (pin 4, clock pin, pin 6 of IC)
int clockPin = 4;//13; //4;
// connect to the DS of 74HC595 (pin 2 pin 3 of IC)
int dataPin =2; //11; //2;
 


void setup() {
  // put your setup code here, to run once:
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
}

// display a number on the digital segment display
void sevenSegWrite(byte digit) {
  // set the latchPin to low potential, before sending data
  digitalWrite(latchPin, LOW);
     
  // the original data (bit pattern)
  shiftOut(dataPin, clockPin, LSBFIRST, seven_seg_digits[digit]);  
 
  // set the latchPin to high potential, after sending data
  digitalWrite(latchPin, HIGH);
}

void loop() {
  // put your main code here, to run repeatedly:

digitalWrite(11, HIGH);

for (byte digit = 10; digit > 0; --digit) {
    delay(1000);
    sevenSegWrite(digit - 1); 
  }
digitalWrite(11, LOW);

digitalWrite(12, HIGH);

for (byte digit = 10; digit > 0; --digit) {
    delay(1000);
    sevenSegWrite(digit - 1); 
  }
digitalWrite(12, LOW);

digitalWrite(13, HIGH);

for (byte digit = 10; digit > 0; --digit) {
    delay(1000);
    sevenSegWrite(digit - 1); 
  }

digitalWrite(13, LOW);

}