Arduino Source Code

int rot = 1;
int gelb = 2;
int gruen = 3;

int button = 4;

void setup() {
 pinMode(rot, OUTPUT);
 pinMode(gelb, OUTPUT);
 pinMode(gruen, OUTPUT);

 // The button should measure inputs
 pinMode(button, INPUT);

 // First set the traffic light to RED
 digitalWrite(rot, HIGH);
 digitalWrite(gelb, LOW);
 digitalWrite(gruen, LOW);
}

void loop() {

 // Here it is checked if the button is pressed
 if(digitalRead(button) == HIGH) {

   delay(5000);

   // ROT zu GRUEN
   digitalWrite(rot, HIGH);
   digitalWrite(gelb, HIGH);
   digitalWrite(gruen, LOW);

   delay(1000);

   digitalWrite(rot, LOW);
   digitalWrite(gelb, LOW);
   digitalWrite(gruen, HIGH);

   delay(5000);


   // green to red
   digitalWrite(rot, LOW);
   digitalWrite(gelb, HIGH);
   digitalWrite(gruen, LOW);

   delay(1000);


   digitalWrite(rot, HIGH);
   digitalWrite(gelb, LOW);
   digitalWrite(gruen, LOW);
 }
}

• At the beginning of the loop()-function it is queried each time whether the button is pressed.
• digitalRead(button) reads the current state of the button. If pressed, the function returns HIGH, otherwise LOW.
• To check if the button was pressed digitalRead(button) has to be compared with HIGH. The comparison is done with two equals == (comparison operator). One equals= is an assignment, such as int red = 13.