#define ntc_pin A5 // Pin,to which the voltage divider is connected
#define vd_power_pin 2 // 5V for the voltage divider
#define nominal_resistance 10000 //Nominal resistance at 25⁰C
#define nominal_temeprature 25 // temperature for nominal resistance (almost always 25⁰ C)
#define samplingrate 5 // Number of samples
#define beta 3950 // The beta coefficient or the B value of the thermistor (usually 3000-4000) check the datasheet for the accurate value.
#define Rref 10000 //Value of resistor used for the voltage divider
int samples = 0; //array to store the samples
#include <Servo.h>
Servo myservo;
int pos = 0;
void setup(void) {
pinMode(vd_power_pin, OUTPUT);
Serial.begin(9600); //initialize serial communication at a baud rate of 9600
myservo.attach(3);
}
void loop(void) {
uint8_t i;
float average;
samples = 0;
// take voltage readings from the voltage divider
digitalWrite(vd_power_pin, HIGH);
for (i = 0; i < samplingrate; i++) {
samples += analogRead(ntc_pin);
delay(10);
}
digitalWrite(vd_power_pin, LOW);
average = 0;
average = samples / samplingrate;
Serial.println("\n \n");
Serial.print("ADC readings ");
Serial.println(average);
// Calculate NTC resistance
average = 1023 / average - 1;
average = Rref / average;
Serial.print("Thermistor resistance ");
Serial.println(average);
float temperature;
temperature = average / nominal_resistance; // (R/Ro)
temperature = log(temperature); // ln(R/Ro)
temperature /= beta; // 1/B * ln(R/Ro)
temperature += 1.0 / (nominal_temeprature + 273.15); // + (1/To)
temperature = 1.0 / temperature; // Invert
temperature -= 273.15; // convert absolute temp to C
Serial.print("Temperature ");
Serial.print(temperature);
Serial.println(" *C");
delay(2000);
if (temperature<=36){
pos=90;
myservo.write(pos);
delay(15);
} else {
pos=0;
myservo.write(pos);
delay(15);
}
}