Temperature Measurement App

int alarma = 7;
char estado;

void setup(){
  // put your setup code here, to run once:
  Serial.begin(9600);
 pinMode(alarma, OUTPUT);
 
 

}

void loop() {
  // put your main code here, to run repeatedly:

   
  byte sensorValue = analogRead(A0);
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):K
  float voltage = (sensorValue * 5.0) / 1023 ;
  float temp = (voltage - 0.4)*51.28 ;
  // print out the value you read:
  Serial.print(temp);
  Serial.print(" C");
  Serial.print("|");
  
  delay (3000);
 

 if (Serial.available()){
   estado = Serial.read();
 
if (estado == 'A'){
  digitalWrite (alarma, HIGH);
  delay (2000);
}
if (estado == 'B'){
  digitalWrite (alarma, LOW);
  delay (2000);
}
}
 
}