tcDspThermERTJV1G

Introduction

The tcDspThermERTJV1G class is used to compute the temperature for an NTC Thermistor. This implementation assumes the a Panasonic ERTJV1G device with a 25 deg-C resistance of 10K and a beta of 3375.

To compute temperature, the A/D count is first converted to voltage, followed by resistance, and finally temperature.

Voltage at the A/D converter ==> Vadc = (2.0) * (ADC Counts) / 4096 Assumes a 2 Volt reference and 12 bit ADC (such as the TLV254x)

Thermistor resistance ===> Rt = (Rf) * (Vin)/(Vadc) Assumes Vin 1.2 Volt (input voltage to thermistor)

T = 1 / ( (1/T0) + (ln(Rt/Rt0) / beta) )

where T is in degrees Kelvin and Rt0, T0 base resistance and temperature (Kelvin)

The temperature is converted to deg-C prior to storage.

See also:

MityDSP::tcDspThermERTJV1G Class Reference

MityDSP::tcDspThermBase Class Reference

Example

This is a simple example of tcDspThermERTJV1G creation and usage:

 {
     unsigned short myAdcVal0, myAdcVal2;
     float          t0, t2;

     // Create tcDspTherm objects
     //   (Vref=3v, ADC=12 bits, 100 ohn feedback R, default beta)
     tcDspThermERTJV1G myFirstSensor(3.0, 12, 100.0);
     tcDspThermERTJV1G mySecondSensor(3.0, 12, 150.0);  // this one with a 150 ohm feedback

     ...

     // add latest ADC values to sensors
     myFirstSensor->SetSensorVal(myAdcVal0);
     mySecondSensor->SetSensorVal(myAdcVal2);

     ...

     // retrieve latest temperatures
     t0 = myFirstSensor->GetSensorTemp();
     t2 = mySecondSensor->GetSensorTemp();
 }