The Arduino programming language for robots

Fig. 1 Microcontroller Arduino Duemilanove - PLC with which I started studying about Arduino

1. LED Control with PWM signal:

void setup() {
    pinMode(13, OUTPUT);
}
void loop() {
    digitalWrite(13, HIGH);
    delay(1000);
    digitalWrite(13, LOW);
    delay(1000);
}

2. LED control variable intensity:

void setup() {
     pinMode(11, OUTPUT);
}
void loop() {
     for (int i = 0; i < 255; i++){
          analogWrite(11, i);
          delay(50);
     }
     for (int i = 255; i > 0; i--){
          analogWrite(11, i);
          delay(50);
     }
}

3. Sound with Arduino (siren):

void setup() {
    pinMode(11, OUTPUT);
}
void loop() {
    for (int i = 1500; i < 4000; i++) {
        tone(11, i);
        delay(10);
    }
    for (int i = 4000; i > 1500; i--) {
        tone(11, i);
        delay(10);
    }
}