LM35 Temperature Sensor

Temperature sensors are widely used in domestic and industrial applications such as: refrigerators; ovens; HVAC environmental control; in the automotive industry to monitor air intake, coolant or cylinder head temperatures. Even your television has a temperature sensor to shut it down if the internal temperature rises above a certain limit.

The goal of these sensors is to measure heat and ensure that a process is either: staying within a certain range, providing safe use of that application, or meeting a mandatory condition when dealing with extreme heat, hazards, or inaccessible measuring points.

For this project I used a LM35CAZ temperature sensor from Texas Instruments (datasheet). The LM35 series are precision integrated-circuit temperature sensors with an output voltage linearly proportional to the Celsius temperature: 0mV + 10mV/ºCelsius. That is, for each 1ºCelsius increase, the temperature sensor output voltage will raise 10mV. This is when the Arduino and one of its analog inputs comes in.

This is why I love working with this development tool. To build a thermometer you just need:

– 1x Arduino Nano 3.0
– 1x LM35 temperature sensor
– Breadboard and wires

Now you have to replicate the circuit below:

The code follows below:

Now open the serial monitor and watch the magic.

Keep in mind that, depending on which Arduino Nano hardware revision you own, there are two analog pin sequences. Confused? Well, an image worth more than a thousand words:

If you prefer to work with temperatures in Fahrenheit, you can use the formula below to convert the temperature from Celsius to Fahrenheit:
°F = °C x 1.8 + 32

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