//NTC
#define ntc_pin A0 // 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
//NTC
// Display I2C
#include <LiquidCrystal_I2C.h>
#define I2C_ADDR 0x27
#define LCD_COLUMNS 20
#define LCD_LINES 4
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);
//const float BETA = 3950; // should match the Beta Coefficient of the thermistor
//NTC
int samples = 0; //array to store the samples
int average = 0; //array to store the samples
//NTC
/////////////////////////////////////////////////////////////////////////////
void setup()
{
// Init
lcd.init();
lcd.backlight();
//NTC
pinMode(vd_power_pin,OUTPUT);
Serial.begin(9600);
//NTC
}
///////////////////////////////////////////////////////////////////////
void loop()
{
// int analogValue_GT1 = analogRead(A0);
// float celsius_GT1 = 1 / (log(1 / (1023. / analogValue_GT1 - 1)) / BETA + 1.0 / 298.15) - 273.15;
//NTC
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.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(1000);
//NTC
lcd.setCursor(0, 0);
lcd.print("RAW ");
lcd.println(samples);
lcd.setCursor(0, 1);
lcd.print("ADC ");
lcd.println(average, 1);
lcd.setCursor(0, 2);
lcd.print("Resist ");;
lcd.println(average, 1);
lcd.setCursor(0, 3);
lcd.print("Temp ");
lcd.print(temperature, 1);
lcd.println(" *C");
}