Benoit Moreau / Mbed 2 deprecated Lab8_requirement8

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Dependencies:   mbed

main.cpp@0:192d42444e3b, 2019-11-08 (annotated)

Committer:
aahnothebees
Date:
Fri Nov 08 18:54:51 2019 +0000
Revision:
0:192d42444e3b
heelo

Who changed what in which revision?

UserRevisionLine numberNew contents of line
aahnothebees 0:192d42444e3b 1 #include <mbed.h>
aahnothebees 0:192d42444e3b 2 #include <math.h>
aahnothebees 0:192d42444e3b 3
aahnothebees 0:192d42444e3b 4
aahnothebees 0:192d42444e3b 5 float readtempurature(AnalogIn *temp); //function prototype
aahnothebees 0:192d42444e3b 6 /**********************************************************************************************************
aahnothebees 0:192d42444e3b 7 Description: The purpose of this function is display the temperature value in a serial terminal
aahnothebees 0:192d42444e3b 8
aahnothebees 0:192d42444e3b 9 In order for this code to work, you must connect a 10k resistor in series with the thermistor. The wire from A1 on the nucleo f411RE must be connected after the resistor. The voltage being used in this circuit is 3.3V.
aahnothebees 0:192d42444e3b 10 Below you will find a rough drawing of what the circuit should look like
aahnothebees 0:192d42444e3b 11
aahnothebees 0:192d42444e3b 12 3.3V---------Resistor---wire from A1-------Thermistor-------GND
aahnothebees 0:192d42444e3b 13
aahnothebees 0:192d42444e3b 14 Parameters:
aahnothebees 0:192d42444e3b 15
aahnothebees 0:192d42444e3b 16 temp->Defines the pin from which to read data/defines the analog input pin used to measure the voltage of the thermistor
aahnothebees 0:192d42444e3b 17 ->Pins assignments are for a nucleo F411RE
aahnothebees 0:192d42444e3b 18 ->A1 is the pin used for this program
aahnothebees 0:192d42444e3b 19 t->defines the timer object used to calculate the time it takes to run through the the readtermpurature function
aahnothebees 0:192d42444e3b 20
aahnothebees 0:192d42444e3b 21 Returns:
aahnothebees 0:192d42444e3b 22 Nothing
aahnothebees 0:192d42444e3b 23 **********************************************************************************************************/
aahnothebees 0:192d42444e3b 24 Timer t;//defines a timer object
aahnothebees 0:192d42444e3b 25 int main(){
aahnothebees 0:192d42444e3b 26 AnalogIn temp (A1); //defines pin A1 on the nucleo F411RE as an analog input
aahnothebees 0:192d42444e3b 27 //for(;;){ //for-loop that will allow the program to run through multiple iterations
aahnothebees 0:192d42444e3b 28 float tempurature;
aahnothebees 0:192d42444e3b 29 t.start();//starts the timer
aahnothebees 0:192d42444e3b 30 tempurature=readtempurature(&temp);
aahnothebees 0:192d42444e3b 31 printf("The tempurature is: %f\n",tempurature);//prints the tempurature in celcius to the serial terminal
aahnothebees 0:192d42444e3b 32 t.stop();//stops the timer
aahnothebees 0:192d42444e3b 33 printf("The time taken was %f seconds\n", t.read()); //prints the time it took to run through the readtempurature(&temp) function to the serial terminal
aahnothebees 0:192d42444e3b 34 wait(0.5); //waits for half a second before running the next iteration
aahnothebees 0:192d42444e3b 35 // }
aahnothebees 0:192d42444e3b 36 }
aahnothebees 0:192d42444e3b 37 /**********************************************************************************************************
aahnothebees 0:192d42444e3b 38 Description: The purpose of this function is to calculate the temperature being read by the thermistor
aahnothebees 0:192d42444e3b 39 In order for this code to work, you must connect a 10k resistor in series with the thermistor. The wire from A1 on the nucleo f411RE must be connected after the resistor. The voltage being used in this circuit is 3.3V.
aahnothebees 0:192d42444e3b 40 Below you will find a rough drawing of what the circuit should look like
aahnothebees 0:192d42444e3b 41
aahnothebees 0:192d42444e3b 42 3.3V---------Resistor---wire from A1-------Thermistor-------GND
aahnothebees 0:192d42444e3b 43
aahnothebees 0:192d42444e3b 44 Parameters:
aahnothebees 0:192d42444e3b 45
aahnothebees 0:192d42444e3b 46 temp->Defines the analog input pin used to measure the voltage of the thermistor
aahnothebees 0:192d42444e3b 47
aahnothebees 0:192d42444e3b 48
aahnothebees 0:192d42444e3b 49 Returns:
aahnothebees 0:192d42444e3b 50 celcius: Returns the tempurature measured by the thermistor in degrees celsius as a float value
aahnothebees 0:192d42444e3b 51 **********************************************************************************************************/
aahnothebees 0:192d42444e3b 52 float readtempurature(AnalogIn *temp)
aahnothebees 0:192d42444e3b 53 {
aahnothebees 0:192d42444e3b 54 float tempVal; //variable that stores the voltage reading of the thermistor as a value between 1 and zero
aahnothebees 0:192d42444e3b 55 tempVal=temp->read(); //reads the voltage of the thermistor on analog pin 1 of the nucleo f411RE
aahnothebees 0:192d42444e3b 56 float vrt; //variable that stores the actual value of the voltage of the thermistor
aahnothebees 0:192d42444e3b 57 vrt=(tempVal*3.3);//this formula determines the actual voltage of the thermistor
aahnothebees 0:192d42444e3b 58 float top;//variable that defines the numerator of the formula to determine the resistance of the thermistor
aahnothebees 0:192d42444e3b 59 top=(vrt*10000);//numerator of the formula used to determine the thermisistor resistance
aahnothebees 0:192d42444e3b 60 float bottom; //variable that defines the denominator of the formula to determine the resistance of the thermistor
aahnothebees 0:192d42444e3b 61 bottom=(3.3-vrt); //denominator of the formula to determine the thermisistor resistance
aahnothebees 0:192d42444e3b 62 float rt=(top/bottom);//this is the formula to determine the thermisitor resistance
aahnothebees 0:192d42444e3b 63 float A=(3.354016e-3);//Constant A1 in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 64 float B=(2.569650e-4);//Constant B1 in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 65 float C=(2.620131e-6);//Constant C1 in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 66 float D=(6.383091e-8);//Constant D1 in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 67 float ln1=(log(rt/10000)); //First ln operation in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 68 float ln2=log(pow((rt/10000),2));//Second ln operation in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 69 float ln3=log(pow((rt/10000),3));//Second ln operation in the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 70 float denominator=(A+(B*ln1)+(C*ln2)+(D*ln3)); //complete denominator of the formula used to calculate the temperature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 71 float celcius=((1/denominator)-273.15);//completed formula to calculate the tempurature given the resistance of the thermisitor
aahnothebees 0:192d42444e3b 72
aahnothebees 0:192d42444e3b 73 return celcius; //returns the value of the tempurature in degrees celsius
aahnothebees 0:192d42444e3b 74 }
aahnothebees 0:192d42444e3b 75