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Using A TMP36 Temperature Sensor With Arduino

Product TUTORIAL

• Chris @ BCR
• July 7, 2015
• four:10 pm
• 27 Comments

The TMP36 temperature sensor is an piece of cake way to measure temperature using an Arduino! The sensor tin can mensurate a fairly wide range of temperature (-50°C to 125°C), is fairly precise (0.i°C resolution), and is very low price, making information technology a popular choice. In this tutorial nosotros volition go over the basics of hooking the TMP36 upward and writing some basic code to read the analog input it is connected to.

A Few Considerations:
Earlier we leap into getting this TMP36 temperature sensor hooked upwardly at that place are a few points to consider:

• This sensor is non weatherproof, so it will need to be shielded from direct exposure to the elements.

How It Works:
Different a thermistor, the TMP36 does not have a temperature sensitive resistor. Instead this sensor uses the property of diodes; as a diode changes temperature the voltage changes with it at a known charge per unit. The sensor measures the minor alter and outputs an analog voltage between 0 and 1.75VDC based on it. To get the temperature we just need to measure the output voltage and a piddling bit of math!

The Parts Needed:

This tutorial will exist requiring a few common parts:

• 1 x TMP36 Temperature Sensor
• 1 x Arduino Uno or compatible microcontroller
• Hookup Wires – We recommend Premium Male/Male Jumper Wire
• Mounting Plate (optional)

The Schematic

This handy little diagram shows how nosotros volition be connecting everything. Don't worry if it looks a trivial overwhelming, nosotros volition exist going through this stride by footstep!

Step 1 – The TMP36 Temperature Sensor

Since this sensor is very simple and does not crave whatever supporting components we will be directly connecting the sensor to the Arduino. First by bending the legs on the TMP36 sensor and so they will fit into the breadboard.

Step 2 – Powering The Sensor

This sensor has a fairly wide input voltage, meaning it isn't terribly picky almost the voltage required (anywhere betwixt 2.7VDC and 5.5VDC). Nosotros will use the Arduino'south 5VDC power for this tutorial. First by connecting a jumper wire from the Arduino's 5VDC pivot and running information technology to the sensor's "pin 1". Adjacent, run some other jumper wire from one of the Arduino's ground pins to the sensor's "pin 3"

Step three – Connecting The Output

We are going to be using ane of the Arduino'south analog input pins for this tutorial. Run a jumper wire from the sensor'south "pin ii" (the middle pivot) to an analog input. Nosotros will be using analog input 0 in this tutorial.

Stride iv – Double Bank check And Plug It In!

Before nosotros give the Arduino power information technology is always a good thought to become over all of the connections to make sure at that place are no wires in the incorrect spot – sometimes that tin brand for a very expensive mistake!

Step 5 – Starting The Code

                                  void setup() {  // put your setup lawmaking here, to run one time:  }  void loop() {  // put your main lawmaking here, to run repeatedly:  }                              

Now that we have finished with the hookup we need to kickoff writing some code. Nosotros will be using the Arduino IDE, this is available from https://world wide web.arduino.cc/en/Main/Software

We will commencement with the "BareMinimum" sketch found by clicking "File" and selecting Examples / Basic / BareMinimum. This sketch is a keen starting point every bit information technology includes the Setup and Loop functions – we volition write the rest!

Step 6 – Understanding How To Read The Sensor

This sensor is very easy to read – the sensor does all of the hard work and so all we have to do is read the output. Since the output voltage is an analog voltage proportional to the temperature we tin can do some very basic math to take the voltage and turn it into a number that makes more sense.

Pace seven - Writing The Code

We are starting with the BareMinimum Sketch constitute in the IDE, it should look something similar this:

                                  void setup() {  // put your setup code here, to run once:  }  void loop() {  // put your chief code hither, to run repeatedly:  }                              

And so starting time we will need some variables to use:

                                  int sensePin = A0; //This is the Arduino Pivot that volition read the sensor output  int sensorInput; //The variable we will use to shop the sensor input  double temp; //The variable we volition use to store temperature in degrees.    void setup() {  // put your setup lawmaking hither, to run once:  }  void loop() {  // put your chief code here, to run repeatedly:  }                              

We plugged the sensor into analog input 0 then we volition declare this as a variable – this will arrive much easier to change in the hereafter if we always decide to change which pivot the sensor is plugged into. Nosotros as well need ii variables for the data; i will store the initial input from the analog input, and the other volition shop the temperature one time nosotros have converted it to decimal degrees.

Arduino analog inputs practise not need to be configured in the Setup loop, so nosotros will just add some code for starting the serial connection we volition use to output the data.

                                  int sensePin = A0; //This is the Arduino Pin that will read the sensor output  int sensorInput; //The variable we will use to shop the sensor input  double temp; //The variable we will employ to store temperature in degrees.    void setup() {  // put your setup lawmaking hither, to run once:  Serial.brainstorm(9600); //Start the Serial Port at 9600 baud (default)    }  void loop() {  // put your main code here, to run repeatedly:  }                              

Ok at present nosotros tin can read the sensor, this will exist done in the loop.

                                  int sensePin = A0; //This is the Arduino Pin that will read the sensor output  int sensorInput; //The variable nosotros will employ to store the sensor input  double temp; //The variable we will use to shop temperature in degrees.    void setup() {  // put your setup code here, to run one time:  Serial.begin(9600); //Start the Serial Port at 9600 baud (default)    }  void loop() {  // put your main code here, to run repeatedly:  sensorInput = analogRead(A0); //read the analog sensor and store it  }                              

Reading analog inputs is very easy with the Arduino – simply that one line of code!

Now we will use a footling math to convert that data to something a little more familiar:

                                  int sensePin = A0; //This is the Arduino Pin that will read the sensor output  int sensorInput; //The variable nosotros will use to store the sensor input  double temp; //The variable we will use to store temperature in degrees.    void setup() {  // put your setup code here, to run once:  Serial.begin(9600); //Start the Serial Port at 9600 baud (default)    }  void loop() {  // put your primary code here, to run repeatedly:  sensorInput = analogRead(A0); //read the analog sensor and shop information technology  temp = (double)sensorInput / 1024; //find pct of input reading  temp = temp * 5; //multiply by 5V to get voltage  temp = temp – 0.v; //Subtract the get-go  temp = temp * 100; //Convert to degrees    }                              

The analog input gives us a value between 0 and 1023, 0 beingness no voltage and 1023 being 5V. To effigy out what this voltage converts to in degrees Celsius we will need to get-go find the percent of 5V on the input. This can exist done by dividing the sensorInput by 1024.

Every bit nosotros know from the datasheet, the sensor will output 0 – 1.75V over a range of 175 degrees (-50° to 125°) so that ways every 0.01V equals one degree. Nosotros volition need to convert the percentage of input to voltage by multiplying past 5V.

Since we are not measuring 0° – 175° we will demand to shift the output value and so that the minimum reading of -50° equals a voltage reading of 0. Nosotros do this past subtracting 0.5 from the output voltage. Our new value at present ranges from -0.5 to one.25 (which looks remarkably like to our temperature range!)

To convert from millivolts to degrees Celsius we volition need to multiply by 100.

Now that we accept degrees, let's output it via series and then it can be seen from the Arduino Serial Monitor.

                                  int sensePin = A0; //This is the Arduino Pin that volition read the sensor output  int sensorInput; //The variable we will utilize to store the sensor input  double temp; //The variable we will use to shop temperature in degrees.    void setup() {  // put your setup code here, to run once:  Series.begin(9600); //Offset the Serial Port at 9600 baud (default)    }  void loop() {  // put your primary code here, to run repeatedly:  sensorInput = analogRead(A0); //read the analog sensor and store information technology  temp = (double)sensorInput / 1024; //find percentage of input reading  temp = temp * v; //multiply by 5V to become voltage  temp = temp – 0.5; //Subtract the offset  temp = temp * 100; //Convert to degrees    Serial.impress("Current Temperature: ");  Serial.println(temp);  }                              

That's it – we are all washed.

Stride eight – Upload The Code And Test

Now that all of the code has been written it can be uploaded to your Arduino! Click "Upload" button in the top left corner of the Arduino IDE and information technology should upload without any issues. Next, click the "Serial Monitor" push button in the acme right corner (it looks similar a magnifying drinking glass). After a few seconds you should start to see a stream of data announced in the window – that is your temperature in degrees Celsius.

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Source: https://bc-robotics.com/tutorials/using-a-tmp36-temperature-sensor-with-arduino/

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