Q.No.11 - WAP for a junction of crossing traffic light sysytem having two sets of LED (Green, Red and Yellow) total 6 LED and six resisters attach it.
The transition of traffic light should be -
1) Order in Red >Yellow >Green
2) Red for 5 second, yellow - 2sec. and Green- 5 second.
3) Both green should not be on same time.

Sol.- 

int red=2;
int yellow=3;
int green=4;
int red1=5;
int yellow1=6;
int green1=7;
void setup()
{
  pinMode(2,OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
  pinMode(5,OUTPUT);
  pinMode(6,OUTPUT);
  pinMode(7,OUTPUT);
}
void loop()
{
  digitalWrite(red,1);
  digitalWrite(green1,1);
  delay(5000);
  digitalWrite(red,0);
  digitalWrite(green1,0);
  digitalWrite(yellow,1);
  digitalWrite(yellow1,1);
  delay(2000);
  
  digitalWrite(yellow,0);
  digitalWrite(yellow1,0);
  digitalWrite(green,1);
  digitalWrite(red1,1);
  delay(5000);
  digitalWrite(green,0);
  digitalWrite(red1,0); 
}

OUTPUT: