Benoit Moreau
/
Servo_Temp
Servo that moves based on temperature readings from a thermistor
Diff: main.cpp
- Revision:
- 0:e043caac158b
- Child:
- 1:563cf31920da
diff -r 000000000000 -r e043caac158b main.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Wed Nov 13 16:17:15 2019 +0000 @@ -0,0 +1,45 @@ +#include <mbed.h> +#include <math.h> + +float readtempurature(AnalogIn *temp); //function prototype + + +int main() +{ + PwmOut servo(A0); + AnalogIn temp (A1); //defines pin A1 on the nucleo F411RE as an analog input + for(;;){ //for-loop that will allow the program to run through multiple iterations + float tempurature; + float y;//float value that stores the duty-cyle calculated on line 15 + tempurature=readtempurature(&temp); + y = (((0.3*tempurature) + 3)/100); //formula that converts the temperature measured by the thermistor into an equivalent duty-cycle, in order for the servo to display an accurate 1:1 scale, change the constant from 0.3 to 0.05 + servo.period(0.02); // sets the period of the servo PWM to 20 ms as specifed in lesson 7 + servo.write(y); //writes the calculated duty-cycle to the servo + printf("The tempurature is: %f\n",tempurature);//prints the temperature in celcius to the serial terminal + wait(0.5); //waits for half a second before running the next iteration + } +} +float readtempurature(AnalogIn *temp) +{ + float tempVal; //variable that stores the voltage reading of the thermistor as a value between 1 and zero + tempVal=temp->read(); //reads the voltage of the thermistor on analog pin 1 of the nucleo f411RE + float vrt; //variable that stores the actual value of the voltage of the thermistor + vrt=(tempVal*3.3);//this formula determines the actual voltage of the thermistor + float top;//variable that defines the numerator of the formula to determine the resistance of the thermistor + top=(vrt*10000);//numerator of the formula used to determine the thermisistor resistance + float bottom; //variable that defines the denominator of the formula to determine the resistance of the thermistor + bottom=(3.3-vrt); //denominator of the formula to determine the thermisistor resistance + float rt=(top/bottom);//this is the formula to determine the thermisitor resistance + float A=(3.354016e-3);//Constant A1 in the formula used to calculate the temperature given the resistance of the thermisitor + float B=(2.569650e-4);//Constant B1 in the formula used to calculate the temperature given the resistance of the thermisitor + float C=(2.620131e-6);//Constant C1 in the formula used to calculate the temperature given the resistance of the thermisitor + float D=(6.383091e-8);//Constant D1 in the formula used to calculate the temperature given the resistance of the thermisitor + float ln1=(log(rt/10000)); //First ln operation in the formula used to calculate the temperature given the resistance of the thermisitor + float ln2=log(pow((rt/10000),2));//Second ln operation in the formula used to calculate the temperature given the resistance of the thermisitor + float ln3=log(pow((rt/10000),3));//Second ln operation in the formula used to calculate the temperature given the resistance of the thermisitor + 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 + float celcius=((1/denominator)-273.15);//completed formula to calculate the tempurature given the resistance of the thermisitor + + return celcius; //returns the value of the tempurature in degrees celsius +} + \ No newline at end of file