Thank you for the updated version.

Clem

Added a button linked to an interrupt to toggle the displayed value between degrees C, F and K. Updated the post above

Hello, the following two sources (sorry but it is impossible to attach) are the temperature class I use on ChipKit PI - that is 100% compatible with Arduino. It makes available the temperature reading in all the known (by me) formats: Fahrenheit, Celsius, Kelving, Rankine. You can use it as a library in the Arduino IDE or include the two files in your own project as well.

Enrico

Include file

/**
* \file Temperature.h
* \brief Constants and class prototypes
*/

#ifndef Temperature_h
#define Temperature_h

#include <inttypes.h>

//! Constant for Kelvin temperature conversion
#define KELVINC 273

//! Absolute zero value for calculation
#define ABSOLUTE_ZERO_CELSIUS -273.15

//! Celsius temperature offset. Should be calibrated depending on the
//! analog reading from the choosen chip. This value is preset for
//! LM35 temperature sensor.
#define TEMP_OFFSET 10

//! Analog channel for the temperature sensor
#define TEMP_SENSOR A1

class Temperature
{
  public:
    Temperature();
    void CalcTemp(float sensor);
    float Celsius() const;
    float Fahrenheit() const;
    float Kelvin() const;
    float Rankine() const;
  private:
    float _Celsius;
    float _Fahrenheit;
    float _Kelvin;
    float _Rankine;
    float _sensorValue;
};
#endif

Class file

/**
* \file Temperature.cpp
* \brief Class to manage the internal temperature of the devices.
*
* The Temperature class acquires data from an LM35 temperature sensor
*
*/
#include "Temperature.h"

/**
  * \brief Temperature class constructor. Set the analog pin for data reading
  */
Temperature::Temperature() {
}

/**
* \brief Convert the analog value to the respective value.
*
* As the call to the temperature reading is not a high priority task and does
* not need very high responsivity, when the analog data are read they are immediately
* converted to the three temperature scales: Celsius, Kelvin and Farehneit.
*/
void Temperature::CalcTemp(float sensor) {
  _sensorValue = sensor;
  _Celsius = (((_sensorValue / 1024) * 5) * 100) - TEMP_OFFSET; // convert the reading to C
  _Fahrenheit = _Celsius * 1.8 + 32.0; // convert the reading to F
  _Kelvin = _Celsius - ABSOLUTE_ZERO_CELSIUS; // convert the reading to K
  _Rankine = ((_Celsius - ABSOLUTE_ZERO_CELSIUS) * 9) / 5; // convert the reading do R
}

float Temperature::Celsius() const {
  return(_Celsius);
}

float Temperature::Fahrenheit() const {
  return(_Fahrenheit);
}


float Temperature::Kelvin() const {
  return(_Kelvin);
}


float Temperature::Rankine() const {
  return(_Rankine);
}

Usage

In the sketch,

#include "Temperature.h"

Then create a global library instance

//! Internal temperature sensor class instance
Temperature internalTemp;

When needed (in the setup() or loop() functions) call the temperature reading

Here I use the TEMP_SENSOR analog pin value, but you can use your own method

  // Read the actual temperature
  internalTemp.CalcTemp(analogRead(TEMP_SENSOR));

Then everywhere you need you have the converted temperature in all the formats calling the class methods as shown below

Serial.println(internalTemp.Celsius());
Serial.println(internalTemp.Fahrenheit());
Serial.println(internalTemp.Kelvin());
Serial.println(internalTemp.Rankine());

Convert the degrees C to F or K, and display, no problem A push button to switch between the different units sounds fun too!

Robert Peter Oakes that is good for those hotter than (bleep).

Clem