My temperature sensor keeps outputting around 4.7 volts

Projects Programming
1

Hi, i'm completely new to arduino and today i tried to build a lamp that changes color on how hot the temperature sensor is. My code: http://pastecloud.net/deuh0yV7xI

This is just an test document, but the rest works fine. This are the results i get:

Thanks!

2

Please do us all a favour and post the code here to make it easier for everyone. When you do, please use code tags.

3

The code:

const int sensorPin = A0; // pin for the temp sensor
const int baselineTemp = 21.0;
 
const int greenLEDPin = 9;
const int redLEDPin = 11;
const int blueLEDPin = 10;
 
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
 
  pinMode(greenLEDPin, OUTPUT);
  pinMode(redLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);
}
 
void loop() {
  // put your main code here, to run repeatedly:
  int sensorValue = analogRead(sensorPin); // reads the value of the temp sensor
 
 
  float voltage = (sensorValue/1024.0) * 5.0; // changes the value of the temp sensor to a voltage between 0 and 5
 
  Serial.print(voltage); Serial.println(" Volts");
 
  float temperature = (voltage - .5) * 100; // changes the voltage to the real temperature
 
  Serial.println(temperature); Serial.println(" Degrees C");
 
  float temperatureDifference = temperature - baselineTemp; // checks how much degrees celcius the temperature is above the baseLineTemp so everything above the baselinetemp is making the RGB led more red
  if(temperatureDifference <= 0){
    temperatureDifference = 0;
  }else if(temperatureDifference > 10){
    temperatureDifference = 10;
  }
 
  float scale = temperatureDifference * 2;
 
  analogWrite(redLEDPin, scale * 25); // changes the scale from the temperature to a value that the RGB led can use
  analogWrite(blueLEDPin, 250 - (scale * 25));
  analogWrite(greenLEDPin, 0);
}
4

What does your voltmeter say? What kind of sensor are you using? How is it hooked up?

5

Display to your serial monitor the raw reading from analog read (before any calculations).
Does it change as the the temp. sensor is heated and cooled?

What sensor are you using? Is it a thermistor? What is its resistance? How do you have it connected to the arduino?

You may want to use a good thermometer and celebrate that input using the map() function.