Null Pointer Exception with Arduino Communication

hi

study this code if you understand it then you can code whatever you need via serial

//--------------------------------------------
//  Ardino code**
//---------------------------------------------

#include <SoftwareSerial.h>
#include <Wire.h>

SoftwareSerial mySerial(11, 12); // RX, TX

int red_led = 3;
int green_led = 6;
int blue_led = 5;
int int_1 = 0;
int int_2 = 0;
int int_3 = 0;
const byte number_of_chars = 32;
char receivedChars[number_of_chars];
boolean new_data = false;

void setup() {
  mySerial.begin(9600); // Set the baudrate equal to HC06 setting
  Serial.begin(9600);
  pinMode(red_led, OUTPUT);
  pinMode(green_led, OUTPUT);
  pinMode(blue_led, OUTPUT);
}

void loop() {
  receivePacket();
  if (new_data == true) {
    parseData();
    executeParsedData();
    new_data = false;
  }
}

void receivePacket() {
  static boolean receiving = false;
  static byte index = 0;
  char start_mark = '<';
  char end_mark = '>';
  char rc;
  while (mySerial.available() > 0 && new_data == false) {
    rc = mySerial.read();
    if (receiving == true) {
      if (rc != end_mark) {
        receivedChars[index] = rc;
        index++;
        if (index >= number_of_chars) {
          index = number_of_chars-1;
        }
      } else {
        receivedChars[index] = '\0';
        receiving = false;
        index = 0;
        new_data = true;
      }
    } else if (rc == start_mark) {
      receiving = true;
    }
  }
}

void parseData() {
  char * split;
  split = strtok(receivedChars, ",");
  int_1 = atoi(split);
  split = strtok(NULL, ",");
  int_2 = atoi(split);
  split = strtok(NULL, ",");
  int_3 = atoi(split);
}

void executeParsedData() {
  if (int_3 == 0) {
    analogWrite(red_led, 0);
    analogWrite(green_led, 0);
    analogWrite(blue_led, 0);
  } else if (int_3 == 1) {
    analogWrite(red_led, 255);
    analogWrite(green_led, 255);
    analogWrite(blue_led, 255);
  } else if (int_3 == 2) {
    if (int_2 == 0) analogWrite(red_led, int_1);
    if (int_2 == 1) analogWrite(green_led, int_1);
    if (int_2 == 2) analogWrite(blue_led, int_1);
  }
}


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