The following information is a single lesson in a larger project. Find more great projects here.

Project Overview:

In this project, you will turn the Arduino into a love machine! Use a temperature sensor to measure your skin temperature, and register how hot you really are. Even though the Arduino is a digital tool, it can interpret signals from an analog input, like the temperature sensor, using the built in Analog-to-Digital (ADC) converter, accessed through the analog pins.

## Step 1: Project Description

In this project you will turn the Arduino into a love machine! Using a temperature sensor on an analog input, you're going to register just how hot you really are!

In the circuit schematic below, you can see that the temperature sensor is connected to power (5 volts) and ground (0 volts) and the analog pin A0. As temperature rises, the pin connected to A0 increases its voltage.

You can also see that three LEDs are connected to their own digital pins. You will be learning how to interpret a change in voltage at A0 and turn on the three LEDs like a bar graph as temperature rises.

1. Continue to the next step.

## Step 2: Bill of Materials

You will need the following electrical components for this project:

1 temperature sensor

3 red LEDs

3x 220 ohm resistors ...and of course your Arduino Uno board and a breadboard!

If you have a physical kit and are building the project at your desk, you will also need paper, scissors, and markers to make an interface for the Love-o-Meter.

1. Can you match each component on the list to its location on the breadboard?

2. Continue to the net step.

## Step 3: Analog Pins

While switches and buttons are great, there’s a lot more to the physical world than on and off. Even though the Arduino is a digital tool, it’s possible for it to get information from analog sensors to measure things like temperature or light. To do this, you’ll take advantage of the Arduino’s built-in Analog-to-Digital Converter (ADC).

1. Analog-in pins A0 to A5 can interpret voltages between 0 and 5 V, and translate that voltage to a value between 0 and 1023 for the Arduino sketch to use.

2. The analog pins can only be used to read information from sensors, and not to write information to outputs.

3. Identify the row of analog input pins on the Arduino Uno in the Workplane.

4. Continue to the next step.

## Step 4: Temperature Sensor

You’ll be using a temperature sensor to measure how warm your skin is. This component outputs a changing voltage depending on the temperature it senses. It has three pins: one that connects to ground, another that connects to 5 volts, and a third that outputs a variable voltage to your Arduino. You can think of it as a powered component that outputs a variable voltage.

1. Find the temperature sensor in the Components + menu. More information is available in the "All Components" tab.
2. In the sketch for this project, you’ll read the sensor’s voltage at analog pin A0 and use it to turn LEDs on and off, indicating how warm you are.
3. There are several different models of temperature sensor. This model, the TMP36, is convenient because it's output voltage is directly proportional to temperature in degrees Celsius.
4. Continue to the next step.

## Step 5: Serial Monitor

The Arduino IDE comes with a tool called the serial monitor that enables you to report back results from the microcontroller. Using the serial monitor, you can get information about the status of sensors, and get an idea about what is happening in your circuit and code as it runs.

1. In the simulator, open the Code Editor window and find the "Serial Monitor" button.
2. In Arduino IDE on your computer, the serial monitor is accessed using an icon in the top right corner.
3. Continue to the next lesson to learn how to assemble the circuit.

Next Lesson:Setting up the Circuit