NTC Thermistor Integration

Using Arduino Sensors
17

OK, it turns out that Rtop was indeed wrong. 3500 instead of 350. I apologize for that. Also turns out that Rbottom was off reported resistance by the 1% it said it could have, so I replaced it. Now, here is the following to report:

#include <math.h>

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

int delaySeconds = 5;
int masterDelay = 1000 * delaySeconds;
float Rtop = 3500;
float Vin = 5;                            // input voltage
  
void loop() {
  float sensorValue = analogRead(A0);                    // read sensor
  float Vout = (sensorValue/1024) * Vin;
  float Rbottom = -Rtop + Rtop * (Vin/Vout);
  // float myTemp = (-32.228 * log(Rtop) + 323.17);          // thermistor trendline
  float VRatio = Vout/Vin;
  float RRatio = Rtop/(Rtop + Rbottom);
  
  Serial.print("SensorValue: ");
  Serial.print(sensorValue);
  
  Serial.print("/Vout: ");
  Serial.print(Vout);

  Serial.print("/Rbottom: ");
  Serial.print(Rbottom);
  
  Serial.print("/VoltRatio: ");
  Serial.print(VRatio);
  
  Serial.print("/RRatio: ");
  Serial.print(RRatio);  
   
  
  Serial.println("");
  delay(masterDelay);
}

Result: SensorValue: 403.00/Vout: 1.97/Rbottom: 5393.30/VoltRatio: 0.39/RRatio: 0.39

So the ratios are good. The measured Voltage is good. The Rbottom is wrong though. It's measured at 2150, reported through the math at 5393.30, which is 2.5x what it should be.

Didn't take any pictures as it is taking shape now.