Export CSV data to Excel in Separate Columns

Hello,

I'm attempting to export serial data to Excel into different columns. Right now, my code allows for all the data to be exported as a .csv file into Excel with all data in the A Column; however, I'm wanting to import timestamps in Column A with Analog values in Column B. Any help would be greatly appreciated!

By the way, my current code is a modified version from the Arduino Cookbook (I'm very new to Processing and programming in general):

1. import processing.serial.*;
   import java.text.*;
   import java.util.*;
   
   PrintWriter output;
   DateFormat fnameFormat = new SimpleDateFormat("yyMMdd_HHmm");
   DateFormat  timeFormat = new SimpleDateFormat("hh:mm:ss:SSS");
   
   String fileName;
   
   Serial myPort;        // Create object from Serial class
   short portIndex = 2;  // select the com port, 0 is the first port
   char HEADER = 'H';
   
   void setup()
   {
     size(200, 200);
     // Open whatever serial port is connected to Arduino.
     String portName = Serial.list()[portIndex];
     println(Serial.list());
     println(" Connecting to -> " + Serial.list()[portIndex]);
     myPort = new Serial(this, portName, 115200);
     Date now = new Date();
     fileName = fnameFormat.format(now);
     output = createWriter(fileName + ".csv"); // save the file in the sketch folder
   }
   
   void draw()
   {
     int val;
     String time;
   
     if ( myPort.available() >= 15)  // wait for the entire message to arrive
     {
       if( myPort.read() == HEADER) // is this the header
       {
         String timeString = timeFormat.format(new Date());
         println("Message received at " + timeString);
         val = readArduinoInt();
         output.println(timeString);
         // header found
         // get the integer containing the bit values
          val = readArduinoInt();
         // print the analog value
         for(int i=0; i < 1; i ++){
           val = readArduinoInt();
           println(val);
           output.println( val);
         }
       }
     }
   }
   
   void keyPressed() {
     output.flush(); // Writes the remaining data to the file
     output.close(); // Finishes the file
     exit(); // Stops the program
   }
   
   // return the integer value from bytes received on the serial port
   // (in low,high order)
   int readArduinoInt()
   {
     int val;      // Data received from the serial port
   
     val = myPort.read();          // read the least significant byte
     val =  myPort.read() * 256 + val; // add the most significant byte
     return val;
   }