thermistor.h

00001 /** Measuring temperature with thermistor
00002  *
00003  * Example of use:
00004  * @code
00005  * #include "mbed.h"
00006  * #include "thermistor.h"
00007  *
00008  * Serial pc(USBTX, USBRX); // serial communication
00009  *
00010  * int main() {
00011  *     Thermistor my_thermistor(A5, 10000, 3950, 4700); // instantiate the sensor object (on pin A5, nominal resistance is 10kOhms, beta coefficient is 3950 and value of the sacond resistor is 4,7kOhms
00012  *     while(1) {
00013  *         pc.printf("Temperature: %5.1f celsius degrees\r", my_thermistor.temperature());
00014  *         pc.printf("Resistance: %5.1f ohms\r", my_thermistor.resistance());
00015  *         wait_ms(1000);
00016  *     }
00017  * }
00018  * @endcode
00019  */
00020 class Thermistor
00021 {
00022 
00023 public:
00024 
00025     /**
00026      * @param thermistorpin mbed analog pin to which the thermistor is connected to
00027      * @param nominalres resistance of thermistor at 25 celsius degrees
00028      * @param beta beta coefficient of thermistor
00029      * @param seriesresistor value of the resistor connecter with thermistor
00030      */
00031     Thermistor (PinName thermistorpin, int nominalres, int beta, int seriesresistor);
00032 
00033     /**
00034      * @returns temperature in celsius degrees
00035      */
00036     float temperature ();
00037     void get_temperature();
00038     /**
00039      * @returns resistance of thermistor
00040      */
00041     float resistance ();
00042     void init();
00043 
00044 private:
00045 
00046     int temperaturenominal;
00047     AnalogIn thermistorpin;
00048     int nominalres;
00049     int beta;
00050     int seriesresistor;
00051     float temp;
00052     float res;
00053     float steinhart;
00054     int a;
00055 
00056 };