KY-013 Temperature sensor (NTC)

This module contains an NTC thermistor that can measure temperatures in the range from -55°C to +125°C. An NTC thermistor (Negative Temperature Coefficient) has the property that its resistance decreases as the temperature increases. This change in the resistance value makes it possible to calculate the corresponding temperature.

The relationship between temperature and resistance is not linear, but can be approximated mathematically. The change in resistance can be determined by using a voltage divider. A voltage divider consists of a known fixed resistance and the variable resistance of the thermistor. When a voltage is applied to the voltage divider, the voltage is divided according to the resistance values. By measuring the voltage across the thermistor, the current resistance can be calculated.

These resistance values can then be converted into temperatures. The exact calculation method and the mathematical approach for determining the temperature are described in the enclosed code examples. This module is ideal for applications where precise temperature measurements are required, such as in climate controls, monitoring systems and other temperature-dependent processes. Due to its high accuracy and wide measuring range, it offers a reliable solution for many temperature measurement tasks.

Pin assignment

Example code

For the following code example an additional library is needed:

Adafruit_ADS1x15 by Adafruit | published under the BSD License.

The example below uses this library - for this we recommend to download it from Github, unzip it and copy it to the Arduino library folder which is located by default at (C:\User[username]\Documents\Arduino\libraries) so that it is available for this code example and following projects. Alternatively, this is also included in the download package below as well.

The program measures the current voltage value at the NTC, calculates the temperature and translates the result to °C for serial output.

#include <Adafruit_ADS1X15.h>
#include <math.h>

Adafruit_ADS1115 ads;

void setup(void)
{
  Serial.begin(9600);
  
  Serial.println("Values of analog input A1 of ADS1115 are read and output");
  Serial.println("ADC Range: +/- 4.096V 1 bit = 0.125mV");
  
  // This module has signal amplifiers at its analog inputs, whose
  // amplification can be configured via software in the ranges below
  // can be configured.
  // This is desired in case a certain voltage range is expected // as measurement result and
  // range is expected as a measurement result and thus a higher resolution of the signal is
  // is obtained.
  // Gain=[2/3] is selected as default gain and can be changed by commenting out // to another gain.
  // to change to a different gain.
  // ADS1115
  // -------
  // ads.setGain(GAIN_TWOTHIRDS); // 2/3x gain +/- 6.144V 1 bit = 0.1875mV
  // ads.setGain(GAIN_ONE); // 1x gain +/- 4.096V 1 bit = 0.125mV
  // ads.setGain(GAIN_TWO); // 2x gain +/- 2.048V 1 bit = 0.0625mV
  // ads.setGain(GAIN_FOUR); // 4x gain +/- 1.024V 1 bit = 0.03125mV
  // ads.setGain(GAIN_EIGHT); // 8x gain +/- 0.512V 1 bit = 0.015625mV
  // ads.setGain(GAIN_SIXTEEN); // 16x gain +/- 0.256V 1 bit = 0.0078125mV
  
  ads.begin();
}

void loop(void)
{
  uint16_t adc1;
  float voltage1;
  float gain_conversion_factor;
  
  // The "ads.readADC_SingleEnded(0)" command is the actual operation that starts the measurement in the ADC.
  // the "0" as variable for this function defines the used channel which should be measured
  // If e.g. the third channel shall be measured, this variable has to be replaced with "3
  adc1 = ads.readADC_SingleEnded(1);
  
  // Conversion of the recorded values into a voltage.
  voltage1 = ads.computeVolts(adc1);
  
  // Output the values to the serial interface
  Serial.print("Analog input 1: "); Serial.print(voltage1); Serial.println(" V");
 
  double Temp;
  Temp = ((voltage1 / 3300) * 10000) / (1 - (voltage1 / 3300));
  Temp = 1 / ((1/298.15) + (1 / 3950.0) * log(Temp / 10000));
  Temp = Temp - 273.15;
  
  Serial.print("Current temperature is:");
  Serial.print(Temp);
  Serial.println("°C");
  Serial.println("---------------------------------------");

  delay(1000);
}

Sample program download

KY013-Arduino.zip