PA fan control

VISHAY NTC 0,2-10k

NTC Thermistor VISHAY 2381 640 64103   10000 Ohm B25/85= 3977K  Kennlinie R25 = 4103 

   Rt=$C$6*EXP($G$4+$G$5/B9-$G$6/(B9*B9)-$G$7/(B9*B9*B9))

300_c_VISHAY-x_NTC 2381 640 3-4-6 Datenblatt 10k NTC-02 serie_2a.xls

107) Measuring temperature with NTC-The Steinhart-Hart Formula

//Measure NTC value
byte NTCPin = A0;
const int SERIESRESISTOR = 10000;
void setup()
{
	Serial.begin(9600);
}
void loop()
{
	float ADCvalue;
	float Resistance;
	ADCvalue = analogRead(NTCPin);
	Serial.print("Analog value ");
	Serial.print(ADCvalue);
	Serial.print(" = ");
//convert value to resistance
	Resistance = (1023 / ADCvalue) - 1;
	Resistance = SERIESRESISTOR / Resistance;
	Serial.print(Resistance);
	Serial.println(" Ohm");
	delay(1000);
}
//end program

//---------------
byte NTCPin = A0;
#define SERIESRESISTOR 10000
#define NOMINAL_RESISTANCE 10000
#define NOMINAL_TEMPERATURE 25
#define BCOEFFICIENT 3950

void setup()
{
Serial.begin(9600);
}
void loop()
{
float ADCvalue;
float Resistance;
ADCvalue = analogRead(NTCPin);
Serial.print("Analog value ");
Serial.print(ADCvalue);
Serial.print(" = ");
//convert value to resistance
Resistance = (1023 / ADCvalue) - 1;
Resistance = SERIESRESISTOR / Resistance;
Serial.print(Resistance);
Serial.println(" Ohm");

float steinhart;
steinhart = Resistance / NOMINAL_RESISTANCE; // (R/Ro)
steinhart = log(steinhart); // ln(R/Ro)
steinhart /= BCOEFFICIENT; // 1/B * ln(R/Ro)
steinhart += 1.0 / (NOMINAL_TEMPERATURE + 273.15); // + (1/To)
steinhart = 1.0 / steinhart; // Invert
steinhart -= 273.15; // convert to C

Serial.print("Temperature ");
Serial.print(steinhart);
Serial.println(" oC");
delay(1000);
}
//-------------

float sample(byte z)
/* This function will read the Pin 'z' 5 times and take an average.
 */
{
	byte i;
	float sval = 0;
	for (i = 0; i < 5; i++)
	{
	sval = sval + analogRead(z);// sensor on analog pin 'z'
	}
	sval = sval / 5.0;    // average
	return sval;
}

1) Steinhart–Hart model, using A, B, C parameters

// TPin = Analog Pin 
// THERMISTOR = NTC nominal value that is measured at 25*C
// R1 = R Serries
// A, B , C = the Steinhart–Hart coefficients, which vary depending on the type and model of thermistor and the temperature range of interest.

float f_ReadTemp_ThABC(byte TPin, long THERMISTOR, float R1, float A, float B, float C) {
 
  int Vo = analogRead(TPin);

  float Resistance = (1023 / (float)Vo) - 1;	           // for pull-up configuration
  float R2 = R1 / Resistance;
  
  float logR2 = log(R2);				   // Pre-Calcul for Log(R2)
  float T = (1.0 / (A + B*logR2 + C*logR2*logR2*logR2)); 
  T =  T - 273.15;					   // convert Kelvin to *C

  return T;
}

// TPin = Analog Pin 
// THERMISTOR = NTC nominal value that is measured at 25*C
// R1 = R Serries
// BETA = the coefficient of the thermistor (3950 is a common value).
// TEMPNOMINAL = usual is 25 (*C)

float f_ReadTemp_Th(byte TPin, long THERMISTOR, float R1, float BETA, int TEMPNOMINAL) {
  
  int Vo = analogRead(TPin);

  float Resistance = (1023 / (float)Vo) - 1;	// for pull-up configuration
  float R2 = R1 / Resistance;
  
  float steinhart;
  steinhart = R2 / THERMISTOR;     		// (R/Ro)
  steinhart = log(steinhart);                  	// ln(R/Ro)
  steinhart /= BETA;                   		// 1/B * ln(R/Ro)
  steinhart += 1.0 / (TEMPNOMINAL + 273.15); 	// + (1/To)
  steinhart = 1.0 / steinhart;                 	// Invert
  steinhart -= 273.15;     			// convert Kelvin to *C
  return steinhart;
}

/*

  Thermistor based temperature sensor.

  10k NTC Thermistor:
    SparkFun SEN-00250
    Mouser P/N 474-SEN-00250
    Vishay part #: NTCLE100E3103JB0 

  Circuit:
    10.09 k resistor  (10,090 ohms)
  
*/

//////////////////////////////////////////////////////////////////////////////
// TimerA
// 10000000 us = 10000 ms = 10 sec = 0.1 Hz 
// 1000000 us = 1000 ms = 1 sec = 1 Hz
// 100000 us = 100 ms = 0.1 sec = 10 Hz
// 10000 us = 10 ms = 0.01 sec = 100 Hz
// 1000 us = 1 ms = 0.001 sec = 1 kHz
// 100 us = 0.1 ms = 0.0001 sec = 10 kHz
const unsigned long timerA = 2000;  
unsigned long timerAlap = millis();  // timer
/////////////////////////////////////////////////////////////////////////
const byte pinBuiltInLED = 13;
/////////////////////////////////////////////////////////////////////////
// Global variables for blinkLEDnoDelay()
unsigned long LEDblinkPeriod = 8;
unsigned long LEDblinkLast = 0;
byte LEDblinkPWM = 0;
bool LEDblinkState = false;
byte LEDlastMode = 0;
void blinkLEDnoDelay(byte pin, byte mode);
/////////////////////////////////////////////////////////////////////////
// 10k NTC Thermistor  NTCLE100E3103JB0
byte pinThermister = A0;
float R1 = 10090.0;   // 10,090 ohm resister in Thermister voltage divider circuit.


void setup () {
  pinMode(pinBuiltInLED, OUTPUT);
  delay(1);
  pinMode(pinThermister, INPUT);
  delay(1);

  //  DEFAULT: analog reference of 5 volts on 5V Arduino boards 
  analogReference(DEFAULT);
  delay(1);

  Serial.begin(9600);
  while (!Serial) {
    digitalWrite(pinBuiltInLED, HIGH);
    delay(1);
    digitalWrite(pinBuiltInLED, LOW);
  }
  Serial.println("\nSerial ready");

  timerAlap = millis(); // reset the timer
} // setup()


void loop() {

  //  Timer A
  if (timerAlap > millis())  timerAlap = millis();
  if (millis() - timerAlap > timerA) { 
    digitalWrite(pinBuiltInLED, HIGH);
    // Take a reading
    float dTempF = GetThermisterTempF(pinThermister);
    Serial.print("Temperature: "); 
    Serial.print(dTempF);
    Serial.println(" F"); 
    digitalWrite(pinBuiltInLED, LOW);
    timerAlap = millis(); // reset the timer
  }
  
} // loop()


////////////////////////////////////////////////////////////////


float GetThermisterTempF(byte pinADC) {
  // Read the 10k NTC Thermistor and return the temperature in F. 
  
  //  10k NTC Thermistor:
  //    SparkFun SEN-00250
  //    Mouser P/N 474-SEN-00250
  //    Vishay part #: NTCLE100E3103JB0 
  
  int iADC = analogRead(pinADC);

  // ADC constants below used for ADC conversion to mV
  // 10 bit, 0 to 1023, or 1024 steps  (Arduino)
  // 12 bit, 0 to 4095, or 4096 steps
  const float FSadc = 1024.0;
  
  // FSmV is the full scale value in mV for the analog input at pinADC.
  // (it is NOT the voltage input to the voltage divider).
  // Use 5000.0 mV for 5 V (Arduino), use 3300 mV for 3.3 V microcontrollers.
  const float FSmV = 5000.0;

  // Calculate the voltage measured at pin ADC.
  float mV = iADC*(FSmV/FSadc);

  // Calculate the circuit resistance from the measured mV (at pinADC)
  // using the voltage divider circuit formula:
  //   Vout = Vin * (R2 / (R1 + R2))
  //   R2 = R1 * (Vin/Vout - 1)
  // Assign to Vin the voltage going into the thermistor voltage divider
  // circuit. Typically this would be the same as FSmV. 
  float Vin = 5000.0;   
  float R2 = R1 * (Vin / mV - 1.0);
  
  // Convert resistance to temperature using Steinhart–Hart equation
  // a1,b1,c1,d1 and equation from Vishay datasheet 
  float a1=3.354016E-3, b1=2.569850E-4, c1=2.620131E-6, d1=6.383091E-8;
  float Rref = 10000.0;   // This is a 10 k thermister
  float T = 1/(a1+b1*log(R2/Rref)+c1*log(R2/Rref)+d1*log(R2/Rref));
  // T is in degrees Kelvin
  T = T - 273.15; // degrees C
  T = (T * 9.0)/ 5.0 + 32.0;    // degrees F
  return T;
} // GetThermisterTempF()

Steinhart-Thermistor (community library)

Steinhart-Thermistor v2

4 coefficients Steinhart version of Thermistor library.

1/T = A + Blog(R/Rt) + Clog(R/Rt)^2 + D**log(R/Rt)^3

In the standard Steinhart-Hart equation the C parameter is set to zero. However, some manufacturers use all 4 coefficients.

Typical usage

Connect a Thermistor to an Analog pin and use the library to get the temperature.

#include "Steinhart-Thermistor.h"

Thermistor Thermistor(A0);

void setup() {
Serial.begin(9600);
}

void loop() {
//Always call calcResistance() first.
//It's the only function that read the ADC value.
//Otherwise you could get a different value for each temperature unit.
//You can specify a number of samples. Default = 1.
Thermistor.calcResistance();
Serial.print("Thermistor resistance: ");
Serial.println(Thermistor.getResistance());
Serial.print("Volts: ");
Serial.println(Thermistor.getVolts());
Serial.print("Analog value at pin: ");
Serial.println(Thermistor.getAval());
Serial.print("Kelvin: ");
Serial.println(Thermistor.getTempK());
Serial.print("Celsius: ");
Serial.println(Thermistor.getTempC());
Serial.print("Fahrenheit: ");
Serial.println(Thermistor.getTempF());
delay(1000);
}

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