Geiger-Muller counter code

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//This code belongs to the following tutorial video: https://youtu.be/l9-wzEY1Ehg
/*
Please consider buying the parts using these affiliation links to support me:
Arduino: https://www.banggood.com/custlink/33KKF85c3i
LCD: https://www.banggood.com/custlink/KKmm5oMimv
GM Board: https://www.banggood.com/custlink/33vDVL2V12
Am-241 Source: https://www.banggood.com/custlink/DG3mFO2OIj
*/


/*
 *Pins for the NOKIA LCD:
 *PIN_SCE   7 //Pin 3 on LCD
 *PIN_RESET 6 //Pin 4 on LCD
 *PIN_DC    5 //Pin 5 on LCD
 *PIN_SDIN  4 //Pin 6 on LCD
 *PIN_SCLK  3 //Pin 7 on LCD
 *
 *PIN for the GM board: Pin 0 on Arduino, VIN on the GM board
 *
 * 5V and GND should be obvious :)
 */


#include <PCD8544.h>
#include <SPI.h>
#define integratingTime 15000  //Logging period in milliseconds
#define oneMinute 60000  //One minute

unsigned long counts = 0;     //variable for GM Tube events
unsigned long events = 0;
unsigned long cpm = 0;        //variable for CPM
unsigned int multiplier;  //variable for calculation CPM in this sketch
unsigned long previousMillis;  //variable for time measurement
double avgCounts = 0;
double avgCPM = 0;
double avgUSV = 0;
double sumCPM = 0;
double sumUSV = 0;
double uSv = 0;
double dose = 0;

const int ledPin =  9;

static PCD8544 lcd;


void tube_impulse() //subprocedure for capturing events from GM board
{
  counts++;
  events++;
}


void setup() {
  // PCD8544-compatible displays may have a different resolution...
  lcd.begin(84, 48);

  counts = 0;
  cpm = 0;
  multiplier = oneMinute / integratingTime;      //calculating multiplier, depend on your log period
  Serial.begin(9600);
  attachInterrupt(0, tube_impulse, FALLING); //define external interrupts
  pinMode(ledPin, OUTPUT);
  Serial.println("GM Tube - Send 's' to start...");
}


void loop()
{

withserialPort();

}


void withserialPort()
  {

  if (Serial.available() > 0) {
      lcd.setCursor(0, 4); //row 5
      lcd.print("Counts: ");
      lcd.print(events);

    char cin = Serial.read();
    if(cin = 's'){
     while(Serial.read() != 'N') {

                 lcd.setCursor(0, 4); //row 5
                 lcd.print("Counts: ");
                 lcd.print(events);

                unsigned long currentMillis = millis();

                if(currentMillis - previousMillis > integratingTime){

                  avgCounts++;
                  previousMillis = currentMillis;
                  cpm = counts * multiplier; //cpm * 60/15 = cpm * 4

                  uSv =( cpm  / 151.0);


                  sumCPM = (double)cpm + sumCPM;
                  sumUSV = uSv + sumUSV;

                  avgCPM = sumCPM / avgCounts;
                  avgUSV = sumUSV / avgCounts;




                //print cpm on serial
                Serial.print((currentMillis)/1000);
                Serial.print("\t");
                Serial.print(cpm);
                Serial.print("\t");
                Serial.print(avgCPM);
                Serial.print("\n");





                 //print on LCD
                 lcd.setCursor(0, 0); //row 1
                 lcd.print("S CPM   uSv/hr"); //first row: information
                 lcd.setCursor(0, 1); //row 2
                 lcd.print("N ");
                 lcd.print(cpm);
                 lcd.print("    ");
                 lcd.print(uSv,4);

                 lcd.setCursor(0, 2); //row 3
                 lcd.print("A ");
                 lcd.print(avgCPM,1);
                 lcd.print("  ");
                 lcd.print(avgUSV,4);


                 counts = 0;
              //-------------------------------------



                }
            }
            }
        }
  }