HOW TO MAKE AN ARDUINO TEMPERATURE SENSOR (THERMISTER TUTORIL)

MAKE AN ARDUINO TEMPERATURE SENSOR

(THERMISTER TUTORIL)

Hardware Required

Arduino or Genuino Board
LCD Screen 16 x 2

pin headers to solder to the LCD display pins

10k ohm potentiometer

220 ohm resistor

4.7 K Ohm Resistor

10 uF, 16 V Polarized Capacitor

100k NTC Thermister (3D Printer)

hook-up wires

breadboard.

THERMISTOR

i am using my 3D Printer Hot end Thermistor the resister value is 100 K Ohms.   

SCHEMATICS 

R1) The value of R1 will depend on your thermistor. If you use the 100 K Ohms Thermistor, it will be 4.7K Ohms,

R2) The value of R2 is 100 K Ohms Thermistor,

C1) Electrolytic capacitors have a polarity & the value is 10uF 16V. Make sure the stripe on yours matches the one in the picture. 

CONNECT THE CIRCUIT

Connect the thermistor & resistor & capacitor to your Arduino like this

i am using 100 K Ohms NTC Thermistor, so my resistor is  4.7 K Ohms, and The Capacitor Value is 10uF 16V. 

CODE FOR SERIAL MONITOR OUTPUT OF TEMPERATURE READINGS

#define THERMISTOR_PIN 0

#define NUMTEMPS 20

short temptable[NUMTEMPS][2] = {

   {1, 841},

   {54, 255},

   {107, 209},

   {160, 184},

   {213, 166},

   {266, 153},

   {319, 142},

   {372, 132},

   {425, 124},

   {478, 116},

   {531, 108},

   {584, 101},

   {637, 93},

   {690, 86},

   {743, 78},

   {796, 70},

   {849, 61},

   {902, 50},

   {955, 34},

   {1008, 3}

};

void setup()

{

   Serial.begin(9600);

   Serial.println("Starting temperature exerciser.");

}

void loop()

{

   int rawvalue = analogRead(THERMISTOR_PIN);

   int celsius = read_temp();

   int fahrenheit = (((celsius * 9) / 5) + 32);

   Serial.print("Current temp: ");

   Serial.print(celsius);

   Serial.print("C / ");

   Serial.print(fahrenheit);

   Serial.println("F");

   Serial.print("Raw value: ");

   Serial.println(rawvalue);

   Serial.println(" ");

   delay(1000);

}

int read_temp()

{

   int rawtemp = analogRead(THERMISTOR_PIN);

   int current_celsius = 0;

   byte i;

   for (i=1; i<NUMTEMPS; i++)

   {

      if (temptable[i][0] > rawtemp)

      {

         int realtemp  = temptable[i-1][1] + (rawtemp - temptable[i-1][0]) * (temptable[i][1] - temptable[i-1][1]) / (temptable[i][0] - temptable[i-1][0]);

         if (realtemp > 255)

            realtemp = 255; 

         current_celsius = realtemp;

         break;

      }

   }

   // Overflow: We just clamp to 0 degrees celsius

   if (i == NUMTEMPS)

   current_celsius = 0;

   return current_celsius;

}

This program will display Celsius and Fahrenheit and also Raw Value at the same time:

CODE FOR LCD OUTPUT OF TEMPERATURE READINGS

in this code help you to output the temperature readings to a 16X2 LCD Display:

#include <LiquidCrystal.h>

#define THERMISTOR_PIN 0

#define NUMTEMPS 20

short temptable[NUMTEMPS][2] = {

   {1, 841},

   {54, 255},

   {107, 209},

   {160, 184},

   {213, 166},

   {266, 153},

   {319, 142},

   {372, 132},

   {425, 124},

   {478, 116},

   {531, 108},

   {584, 101},

   {637, 93},

   {690, 86},

   {743, 78},

   {796, 70},

   {849, 61},

   {902, 50},

   {955, 34},

   {1008, 3}

};

LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // set up the LCD's number of columns and rows:

void setup()

{

   lcd.begin(16, 2); // Print a message to the LCD

}

void loop()

{

   int rawvalue = analogRead(THERMISTOR_PIN);

   int celsius = read_temp();

   int fahrenheit = (((celsius * 9) / 5) + 32);  

   

   lcd.setCursor(0,0); // set the cursor to column 0, line 1

   lcd.print("Temp = "); // Print a message to the LCD.

   lcd.print(celsius);

   lcd.print("C/"); // Print a message to the LCD.

   lcd.print(fahrenheit);

   lcd.print("F"); // Print a message to the LCD.

   lcd.setCursor(0,1); // (note: line 1 is the second row, since counting begins with 0):

   lcd.print("Raw value: "); // Print a message to the LCD.

   lcd.print(rawvalue);

   lcd.print(" "); // Print a message to the LCD.

   

   delay(1000);

   lcd.clear();

  

}

int read_temp()

{

   int rawtemp = analogRead(THERMISTOR_PIN);

   int current_celsius = 0;

   byte i;

   for (i=1; i<NUMTEMPS; i++)

   {

      if (temptable[i][0] > rawtemp)

      {

         int realtemp  = temptable[i-1][1] + (rawtemp - temptable[i-1][0]) * (temptable[i][1] - temptable[i-1][1]) / (temptable[i][0] - temptable[i-1][0]);

         if (realtemp > 255)

            realtemp = 255; 

         current_celsius = realtemp;

         break;

      }

   }

   // Overflow: We just clamp to 0 degrees celsius

   if (i == NUMTEMPS)

   current_celsius = 0;

   return current_celsius;

}

Video Tutorial of the Temperature Sensor :

Here’s a video so you can watch and see how it works:

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