Temperature Measurement

I wrote a basic program for the Arduino to increase my knowledge of computer programming. I am studying to become a mechanical engineer so computer programming although not a focus of my studies is very important. A moderate knowledge of computer programming aids in  understanding the programs I may use in industry and will allow a solid foundation if I ever need to create my own program for specialized analysis.

I wrote my program by first researching for programs that are already created so I can analyze others' work for well and poorly designed systems. Then I outlined my goals for my program and then using the knowledge collected from research and from my background I wrote a program that I believe meets my goals. While writing my program I annotated each line of code to better understand what the code is doing for later reference and for other's to understand my code easily.

My Written Arduino Code:

//TMP36 Pin Variables

int temperaturePin = 0; 

//the analog pin the TMP36's Vout (sense) pin is connected to the 

//resolution is 10 mV / degree centigrade (500 mV offset) to make 

//negative temperatures an option

/*

 * setup() - this function runs once when you turn your Arduino on

 * We initialize the serial connection with the computer

 */

void setup()

{

  Serial.begin(9600); 

  //Start the serial connection with the computer to view the result 

  //open the serial monitor last button beneath the file bar 

  //(looks like a box with an antennae)

}

void loop()        

// run over and over again

{

  static int t;

  // t is a local variable

  t++; 

 // time increases with each loop

  

 float celsius= getVoltage(temperaturePin); 

 //getting the voltage reading from the temperature sensor

 celsius= (celsius- .5) * 100;          

 //converting from 10 mv per degree wit 500 mV offset

 //to degrees ((volatge - 500mV) times 100)   

                  

float fahrenheit= (celsius*9/5)+32;          

//converting the read temperature from celsius to fahrenheit 

 Serial.println("Time [s]");              

 // prints the label for time 

 Serial.println(t);       

 // prints the time elapsed 

 Serial.println("Temperature [F] and [C], respectively");     

 // prints the label temperature converted and read

 Serial.println(fahrenheit);       

 // printing the temperature in fahrenheit

 Serial.println(celsius);    

 // printing the temperature in celsius 

 Serial.println(" ");            

 // prints a space between each loop to help organize the serial monitor

 delay(993); 

 // delays 1 sec minus the error of approx 7 millisec per loop from the 

 //arduino processing and looping, (error calculated experimentally)

 }

/*

 * getVoltage() - returns the voltage on the analog input defined by

 * pin

 */

float getVoltage(int pin){

 return (analogRead(pin) * .004882814); 

 //converting from a 0 to 1023 digital range to 0 to 5 volts 

 //(each 1 reading equals ~ 5 millivolts

}

My code in action:

Ice on 1/8in Aluminum (only 60 sec intervals displayed)

Time [s]
1
Temperature [F] and [C], respectively
72.96
22.75

Time [s]
60
Temperature [F] and [C], respectively
71.20
21.78


Time [s]
120
Temperature [F] and [C], respectively
68.56
20.31

Time [s]
180
Temperature [F] and [C], respectively
67.68
19.82

Hot tap water poured into plastic bottle:

Time [s]
1
Temperature [F] and [C], respectively
77.35
25.20

Time [s]
2
Temperature [F] and [C], respectively
77.35
25.20

Time [s]
3
Temperature [F] and [C], respectively
77.35
25.20

Time [s]
4
Temperature [F] and [C], respectively
78.23
25.68

Time [s]
5
Temperature [F] and [C], respectively
79.11
26.17

Time [s]
6
Temperature [F] and [C], respectively
79.11
26.17

Time [s]
7
Temperature [F] and [C], respectively
79.99
26.66

Time [s]
8
Temperature [F] and [C], respectively
80.87
27.15

Time [s]
9
Temperature [F] and [C], respectively
80.87
27.15

Time [s]
10
Temperature [F] and [C], respectively
81.75

27.64

My code is based off of the code found at http://www.oomlout.com/oom.php/products/ardx/circ-10. However, I modified the code to be easier to read in the serial monitor output by including the time at which data was collected and labeling the data. I also included measurements in both Celsius and Fahrenheit to save time if conversion was needed. Lastly, I let my program run for an hour so I could calculate the error in the time reading caused by the Arduino looping the program and processing data. I then corrected the delay time to take into account the error for accurate data collection.