const int potpin=A0;
const int led1=9;
const int led2=10;
const int led3=11;
const int buzzer=8;


void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
}

void loop() {
int potvalor=analogRead(potpin);
int pwmvalor=map(potvalor,0,1023,0,255);

analogWrite(led1,pwmvalor);
analogWrite(led2,pwmvalor);
analogWrite(led3,pwmvalor);
Serial.print("Valor de slider--> ");
Serial.println(potvalor);
delay(20);
sirena();
}

void sirena(){
  //subida de volumen
  for(int freq=500; freq<=1000;freq+=10){
    tone(buzzer,freq);
    delay(5);
  }
    //bajada de tono
  for(int freq=1000;freq>=500; freq-=10){
    tone(buzzer,freq);
    delay(5);
  }
}