Tutorial Arduino Controllo Led Con Switch E Potenziometro

#define ledpin 8
#define btnpin 7

int btnval = 0;
int btnst = 0;

void setup() {
  pinMode(ledpin, OUTPUT);
  pinMode(btnpin, INPUT);
  Serial.println(9600);
}

void loop() {  
  btnval = digitalRead(btnpin);
  if (btnval == HIGH & btnst == 0){
    btnst = 1;
    Serial.println(btnst);
  }
  else if (btnval == HIGH & btnst == 1){
    btnst = 0;
    Serial.println(btnst);
  }
  switch (btnst){
    case 0:
    digitalWrite(ledpin, LOW);
    break;
    case 1:
    digitalWrite(ledpin, HIGH);
    delay(analogRead(0));
    digitalWrite(ledpin, LOW);
    delay(analogRead(0));
    break;
  }
  delay(500);
}