/* 
--------------------------------------------  
-------- Begin Initialise Variables --------
--------------------------------------------
*/

//STAGE #1
//define pins
int solenoid_pin = 2;
int hall_effect_sensor = A0;
//add code here

//Sensor readings
//add code here
int hall_effect_reading = 0;
float pendulum_length = 0.23;
int peak_threshold = 520;


/*--------------------------------------------  
-------- End Initialise Variables ----------
--------------------------------------------
*/


/* 
----------------------------------  
-------- Begin Setup Loop --------
----------------------------------
*/

void setup() 
{

  // initialize serial communication at 115200 bits per second.
  Serial.begin(9600);

  //STAGE 2 - pin modes
  //add code here 
  pinMode(solenoid_pin, OUTPUT);
  pinMode(hall_effect_sensor, INPUT);
  
  //Control solenoid
  //add code here
 digitalWrite(solenoid_pin, LOW);
 digitalWrite(solenoid_pin, HIGH);
 delay(1000);
 digitalWrite(solenoid_pin, LOW);
}

/* 
-------------------------------
------- End Setup Loop --------
-------------------------------
*/

/* 
----------------------------------  
-------- Begin Main Loop ---------
----------------------------------
*/ 

  //STAGE 3 - the main loop
void loop() 
{
  // variables for timing
  unsigned long start_time = 0;
  unsigned long current_time = 0;
  unsigned long elapsed_time = 0;

  //add more code here...
  int hall_effect_reading_old = 0;
  int peak_count = 0;
  float gravity = 0;
  float period = 0;
  float average_period = 0;
  float average_period_ms = 0;
  float average_period_s = 0;

  //get start time
  //add code here
  start_time = millis();

  do  {
     //read Hall effects sensor
     //add code here
     hall_effect_reading = analogRead(hall_effect_sensor);

     //get current time
     //add code here
     current_time = millis();

     //calc elapsed time in milliseconds
     //add code here
     elapsed_time = current_time - start_time;

    if ((hall_effect_reading >= peak_threshold) && (hall_effect_reading_old <= peak_threshold));
    { 
      peak_count = peak_count + 1;
    }

    hall_effect_reading_old = hall_effect_reading;

	 //Print data back to the computer
	 //add code here
   Serial.print(elapsed_time);
   Serial.print(',');
   Serial.print(hall_effect_reading);
   Serial.print(',');
   Serial.print(peak_count);
   Serial.print('\n');
	
  } while (elapsed_time <= 10000);

  
  //STAGE 5 - calculate Gravity...
  average_period_ms = 2*elapsed_time/peak_count;
  average_period_s = average_period_ms * 0.001;

  //evaluate gravity
  //g = your calculation here: use the sq() and PI
  gravity = 4*sq(PI)*pendulum_length/average_period_s;

  //STAGE 5b - print your answer...
  Serial.print(gravity);
  
  delay(10000); //wait for 10 seconds - LEAVE THIS FOR RELOAD TO WORK PROPERLY!
}

/* 
----------------------------------  
--------- End Main Loop ----------
----------------------------------
*/