Take pictures without physical buttom - ARDUCAM

I am using the code given by arducam. Only want modify some parts.

I am using an arduino uno R3, ethernet shield w5100 an arducam shield OV2640

// ArduCAM demo (C)2014 Lee
// web: http://www.ArduCAM.com
// This program is a demo of how to use most of the functions
// of the library with a supported camera modules, and can run on any Arduino platform.
//
// This demo was made for Omnivision OV2640 2MP sensor.
// It will run the ArduCAM as a real 2MP digital camera, provide both preview and JPEG capture.
// The demo sketch will do the following tasks:
// 1. Set the sensor to BMP preview output mode.
// 2. Switch to JPEG mode when shutter buttom pressed.
// 3. Capture and buffer the image to FIFO. 
// 4. Store the image to Micro SD/TF card with JPEG format.
// 5. Resolution can be changed by myCAM.set_JPEG_size() function.
// This program requires the ArduCAM V3.1.0 (or later) library and Rev.C ArduCAM shield
// and use Arduino IDE 1.5.2 compiler or above

#include <UTFT_SPI.h>
#include <SD.h>
#include <Wire.h>
#include <ArduCAM.h>
#include <SPI.h>
#include "memorysaver.h"

#if defined(__arm__)
  #include <itoa.h>
#endif

#define SD_CS 9 
// set pin 10 as the slave select for SPI:
const int SPI_CS = 8;

ArduCAM myCAM(OV2640,SPI_CS);

boolean isShowFlag = true;

void setup()
{
  uint8_t vid,pid;
  uint8_t temp; 
  #if defined (__AVR__)
    Wire.begin(); 
  #endif
  #if defined(__arm__)
    Wire1.begin(); 
  #endif
  Serial.begin(115200);
  Serial.println("ArduCAM Start!"); 
  // set the SPI_CS as an output:
  pinMode(SPI_CS, OUTPUT);

  // initialize SPI:
  SPI.begin(); 
  //Check if the ArduCAM SPI bus is OK
  myCAM.write_reg(ARDUCHIP_TEST1, 0x55);
  temp = myCAM.read_reg(ARDUCHIP_TEST1);
  if(temp != 0x55)
  {
  	Serial.println("SPI interface Error!");
  	while(1);
  }
  
  //Change MCU mode
  myCAM.write_reg(ARDUCHIP_MODE, 0x00);


  
  //Check if the camera module type is OV2640
  myCAM.rdSensorReg8_8(OV2640_CHIPID_HIGH, &vid);
  myCAM.rdSensorReg8_8(OV2640_CHIPID_LOW, &pid);
  if((vid != 0x26) || (pid != 0x42))
  	Serial.println("Can't find OV2640 module!");
  else
  	Serial.println("OV2640 detected");
  	
  //Change to BMP capture mode and initialize the OV2640 module	  	
  myCAM.set_format(BMP);

  myCAM.InitCAM();
  
  //Initialize SD Card
  if (!SD.begin(SD_CS)) 
  {
    //while (1);		//If failed, stop here
    Serial.println("SD Card Error");
  }
  else
    Serial.println("SD Card detected!");
}

void loop()
{
  char str[8];
  File outFile;
  byte buf[256];
  static int i = 0;
  static int k = 0;
  static int n = 0;
  uint8_t temp,temp_last;
  uint8_t start_capture = 0;
  int total_time = 0;
  
  
  ARDUCHIP_TRIG = 0x41;
  SHUTTER_MASK = 1;

  //Wait trigger from shutter buttom   
  if(myCAM.read_reg(ARDUCHIP_TRIG) & SHUTTER_MASK)	
  {
    isShowFlag = false;
    myCAM.write_reg(ARDUCHIP_MODE, 0x00);
    myCAM.set_format(JPEG);
    myCAM.InitCAM();

    myCAM.OV2640_set_JPEG_size(OV2640_640x480);
    //myCAM.OV2640_set_JPEG_size(OV2640_1600x1200);
    //Wait until buttom released
    while(myCAM.read_reg(ARDUCHIP_TRIG) & SHUTTER_MASK);
    delay(1000);
    start_capture = 1;
    	
  }
  
    

  if(start_capture)
  {
    //Flush the FIFO 
    myCAM.flush_fifo();	
    //Clear the capture done flag 
    myCAM.clear_fifo_flag();		 
    //Start capture
    myCAM.start_capture();
    Serial.println("Start Capture");     
  }
  
  if(myCAM.read_reg(ARDUCHIP_TRIG) & CAP_DONE_MASK)
  {

    Serial.println("Capture Done!");
    
    //Construct a file name
    k = k + 1;
    itoa(k, str, 10); 
    strcat(str,".jpg");
    //Open the new file  
    outFile = SD.open(str,FILE_WRITE);
    if (! outFile) 
    { 
      Serial.println("open file failed");
      return;
    }
    total_time = millis();
    i = 0;
    temp = myCAM.read_fifo();
    //Write first image data to buffer
    buf[i++] = temp;

    //Read JPEG data from FIFO
    while( (temp != 0xD9) | (temp_last != 0xFF) )
    {
      temp_last = temp;
      temp = myCAM.read_fifo();
      //Write image data to buffer if not full
      if(i < 256)
        buf[i++] = temp;
      else
      {
        //Write 256 bytes image data to file
        outFile.write(buf,256);
        i = 0;
        buf[i++] = temp;
      }
    }
    //Write the remain bytes in the buffer
    if(i > 0)
      outFile.write(buf,i);

    //Close the file 
    outFile.close(); 
    total_time = millis() - total_time;
    Serial.print("Total time used:");
    Serial.print(total_time, DEC);
    Serial.println(" millisecond");    
    //Clear the capture done flag 
    myCAM.clear_fifo_flag();
    //Clear the start capture flag
    start_capture = 0;
    
    myCAM.set_format(BMP);
    myCAM.InitCAM();
    isShowFlag = true;	
  }
}