This is an updated post.
I’m working on an oil temperature thermistor sensor (Part Number 965-531) for rotax 912uls.
I cannot find a data sheet for the part, I only have a graph with resistor to temperature values in the attachments.
I want to interface it with the Arduino, so I can process the data. I followed a tutorial for thermistors from adafruit.
The only difference I can find between the thermistor they are using and mine is the series resistor and the thermistor values(1000ohms).
I used this website to calculate the beta value (NTC Thermistors - Calculate Beta Values | Ametherm)
The values I used
Resistance 1 = 1000
Resistance 2 = 20
Temperature 1 =20
Temperature 2 =160
B = 3548.15
I’m using a program called proteus to simulate its operation with arduino, I have attached a picture at max temp and the results seem to be correct.
Here is the code I’m using
// which analog pin to connect
#define THERMISTORPIN A0
// resistance at 25 degrees C
#define THERMISTORNOMINAL 1000
// temp. for nominal resistance (almost always 25 C)
#define TEMPERATURENOMINAL 25
// how many samples to take and average, more takes longer
// but is more 'smooth'
#define NUMSAMPLES 5
// The beta coefficient of the thermistor (usually 3000-4000)
#define BCOEFFICIENT 3548
// the value of the 'other' resistor
#define SERIESRESISTOR 1000
uint16_t samples[NUMSAMPLES];
void setup(void) {
Serial.begin(9600);
analogReference(EXTERNAL);
}
void loop(void) {
uint8_t i;
float average;
// take N samples in a row, with a slight delay
for (i=0; i< NUMSAMPLES; i++) {
samples[i] = analogRead(THERMISTORPIN);
delay(10);
}
// average all the samples out
average = 0;
for (i=0; i< NUMSAMPLES; i++) {
average += samples[i];
}
average /= NUMSAMPLES;
Serial.print("Average analog reading ");
Serial.println(average);
// convert the value to resistance
average = 1023 / average - 1;
average = SERIESRESISTOR / average;
Serial.print("Thermistor resistance ");
Serial.println(average);
float steinhart;
steinhart = average / THERMISTORNOMINAL; // (R/Ro)
steinhart = log(steinhart); // ln(R/Ro)
steinhart /= BCOEFFICIENT; // 1/B * ln(R/Ro)
steinhart += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
steinhart = 1.0 / steinhart; // Invert
steinhart -= 273.15; // convert to C
Serial.print("Temperature ");
Serial.print(steinhart);
Serial.println(" *C");
delay(1000);
}
I am new to arduino and would like any input.
Thanks
Jason
