temperature-ligths.c

const int   sensorPin           = A0;
const int   ledGreenPin         = 2;
const int   ledYellowPin        = 3;
const int   ledRedPin           = 4;
const float temperatureCorrect  = 19.0;
const float temperatureRaised   = 20.0;

void setup() {
    Serial.begin(9600);
    pinMode(ledGreenPin, OUTPUT);
    pinMode(ledYellowPin, OUTPUT);
    pinMode(ledRedPin, OUTPUT);
    digitalWrite(ledGreenPin, LOW);
    digitalWrite(ledYellowPin, LOW);
    digitalWrite(ledRedPin, LOW);
}

void loop() {

    int sensorVal = analogRead(sensorPin);
    float voltage = (sensorVal / 1024.0) * 5.0;
    float temperature = (voltage - .5) * 100;

    Serial.print("Grados:    ");
    Serial.println(temperature);

    if(temperature <= temperatureCorrect){
        updateLed(ledGreenPin);
    }

    if(temperature > temperatureCorrect && temperature < temperatureRaised){
        updateLed(ledYellowPin);
    }

    if(temperature >= temperatureRaised){
        updateLed(ledRedPin);
    }

    delay(5000);
}

void updateLed(int led){
    digitalWrite(ledGreenPin, LOW);
    digitalWrite(ledYellowPin, LOW);
    digitalWrite(ledRedPin, LOW);
    digitalWrite(led, HIGH);
    Serial.print("Using led: ");
    Serial.println(led);
}