Triggering Stop Watch

/*
To Trigger Stop Watch ON & OFF At Pre Set Rising Voltages.
willeng
11/1/2015
Modified Sketches
Stop Watch To Trigger ON at ref1 Voltage & OFF at ref2 Voltage.
ref1 Turns Stop Watch ON
ref2 Turns Stop Watch OFF
  Arduino Mega 2560
  MAX7219  7 Segment Module  
  VCC  --------------->  5.0V
  DIN  --------------->  Pin 7
  CLK  --------------->  Pin 6
  LOAD  --------------->  Pin 5
  GND  --------------->  GND
  ////////////////////////////////////////////////////////////////////////////////////////////
  Trigger Connections:
  Output From LM2917N (0-5V max) Connected To (Pins A0 & A1)
  Digital Output - 'ref1' (pin 8)
  Digital Output - 'ref2' (pin 9)
  ////////////////////////////////////////////////////////////////////////////////////////////
  
  Interrupt 0 Pin 2 Mega 2560
  Interrupt 5 Pin 18 Mega 2560  
*/

#include "LedControl.h"
#include <plcLib.h>

LedControl lc=LedControl(7,6,5,1);

unsigned int START = 1;  // Trigger Start-up state (START = 1 to automatically start here)
int fsec, sec, minute, i, Start;
long previousMillis = 0;
long interval = 100;

//  Trigger
unsigned int ref1 = 300;  // Example:
//  (ref1) lower threshold = 307
//  (30% of 1024 = 1024 * 0.3 = 307)
//  (ref1) Lower threshold voltage = Vsupply * 0.3
//  (1.5 V if Vsupply = 5 V)
  
unsigned int ref2 = 600;  // (ref2 upper threshold = 717
//  (70% of 1024 = 1024 * 0.7 = 717)
//  Upper threshold voltage = Vsupply * 0.7
//  (3.5 V if Vsupply = 5 V)
//////////////////////////////////////////////////////////////////////////////
void setup()
{
  //  Trigger
  setupPLC();  // Setup inputs and outputs
  ///////////////////////////////////////////////////////////////

  // the zero refers to the MAX7219 number, it is zero for 1 chip
  lc.shutdown(0,false);// turn off power saving, enables display
  lc.setIntensity(0,2);// sets brightness (0~15 possible values)
  lc.clearDisplay(0);// clear screen
  fsec = 0;
  sec = 0;
  minute = 0;
  Start = 0;
  Disp_Data();

  attachInterrupt(0, Trigger, RISING);
  attachInterrupt(5, Trigger, RISING);
}
void loop()
{
  //  Trigger
  in(START);  // Read Start-up state
  inAnalog(A0);  // Read Analogue Input A0
  compareGT(ref1);  // Is Pin A0 > lower threshold?
  out(8);  // Pin 8 = 1 if Pin A0 > 300, Pin 8 = 0 otherwise
  reset(ref1);  // Cancel (ref1)

  inAnalog(A1);  // Read Analogue Input A1
  compareGT(ref2);  // Is Pin A1 > upper threshold?
  out(9);  // Pin 9 = 1 if Pin A1 > 600, Pin 9 = 0 otherwise
  reset(ref2);  // Cancel (ref2)

  //  Max 7219
  if(Start == 1) {
  unsigned long currentMillis = millis();
  if(currentMillis - previousMillis > interval) {
  previousMillis = currentMillis;
  fsec = fsec+10;
  if(fsec == 100) {
  fsec = 0;
  sec = sec+1;
  if (sec == 100) {
  sec = 0;
  minute = minute+1;
  if(minute == 100) minute = 0;
  }
  }
  Disp_Data();
  } 
  }
}

void Trigger(){
if (Start == 1) {
  Start = 0;
}
else if (Start == 0){
  Start = 1;
}
}

void Disp_Data(){
  int ones, tens;
  ones = fsec%10;
  tens = (fsec/10)%10;
  lc.setDigit(0,0,(byte)tens,false);
  ones = sec%10;
  tens = (sec/10)%10;
  lc.setChar(0, 1,'-',false);
  lc.setDigit(0,2,(byte)ones,false);
  lc.setDigit(0,3,(byte)tens,false);

}

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