Bluetooth Nerf Turret

#include <Servo.h>

//-----Declare servos and variables
Servo recoil_servo;
Servo pan_servo;
Servo tilt_servo;

const byte pan_limit_1 = 0;
const byte pan_limit_2 = 180;
const byte tilt_limit_1 = 65;
const byte tilt_limit_2 = 180;
const byte recoil_rest = 180;    // Angle of the servo when at rest
const byte recoil_pushed = 125;  // Angle the servo need to reach to push the dart

//-----Variables related to serial data handling
byte byte_from_app;
const byte buffSize = 30;
byte inputBuffer[buffSize];
const byte startMarker = 255;
const byte endMarker = 254;
byte bytesRecvd = 0;
boolean data_received = false;

//-----Variable related to motor timing and firing
bool is_firing =  false;
bool can_fire =  false;
bool recoiling = false;

unsigned long firing_start_time = 0;
unsigned long firing_current_time = 0;
const long firing_time = 150;

unsigned long recoil_start_time = 0;
unsigned long recoil_current_time = 0;
const long recoil_time = 2 * firing_time;

const byte motor_pin =  12;
boolean motors_ON = false;

//8===========================D

void setup()
{
  //-----define motor pin mode
  pinMode(motor_pin, OUTPUT);
  digitalWrite(motor_pin, LOW);

  //-----attaches servo to pins
  recoil_servo.attach(9);
  pan_servo.attach(10);
  tilt_servo.attach(11);

  //-----starting sequence
  recoil_servo.write(recoil_rest);
  pan_servo.write(90);
  delay(1000);
  tilt_servo.write(105);


  Serial.begin(9600);  // begin serial communication
}

//8===========================D

void loop()
{
  getDataFromPC();
  set_motor();
  if (data_received) {
    move_servo();
    set_recoil();
    set_motor();
  }
  fire();
}

//8===========================D

void getDataFromPC() {

  //expected structure of data [start byte, pan amount, tilt amount, motor on, firing button pressed, end byte]
  //start byte = 255
  //pan amount = byte between 0 and 253
  //tilt amount = byte between 0 and 253
  //motor on = 0 for off - 1 on
  //firing button pressed = 0 for not pressed - 1 for pressed
  //end byte = 254

  if (Serial.available()) {  // If data available in serial

    byte_from_app = Serial.read();   //read the next character available

    if (byte_from_app == 255) {     // look for start byte, if found:
      bytesRecvd = 0;                   //reset byte received to 0(to start populating inputBuffer from start)
      data_received = false;
    }

    else if (byte_from_app == 254) {    // look for end byte, if found:
      data_received = true;                // set data_received to true so the data can be used
    }

    else {                            // add received bytes to buffer
      inputBuffer[bytesRecvd] = byte_from_app;     //add character to input buffer
      bytesRecvd++;                                // increment byte received (this act as an index)
      if (bytesRecvd == buffSize) {    // just a security in case the inputBuffer fills up (shouldn't happen)
        bytesRecvd = buffSize - 1;    // if bytesReceived > buffer size set bytesReceived smaller than buffer size
      }
    }
  }
}

//8===========================D

void move_servo() {
  
  byte pan_servo_position = map(inputBuffer[0], 0, 253, pan_limit_2, pan_limit_1);//convert inputbuffer value to servo position value
  pan_servo.write(pan_servo_position); //set pan servo position
  byte tilt_servo_position = map(inputBuffer[1], 0 , 253, tilt_limit_2, tilt_limit_1); //convert inputbuffer value to servo position value
  tilt_servo.write(tilt_servo_position); //set pan servo position
}

//8===========================D

void set_recoil() {

  if (inputBuffer[3] == 1) {        //if fire button pressed
    if (!is_firing && !recoiling) { //and not already firing or recoiling
      can_fire = true;              //set can fire to true (see effect in void fire())
    }
  }
  else {                  // if fire button not pressed
    can_fire = false;     //set can fire to false (see effect in void fire())
  }
}

//8===========================D

void set_motor() {
  //-----start and stop motors using MOSFET transisitor .

  if (inputBuffer[2] == 1) {                //if screen touched
    digitalWrite(motor_pin, HIGH);          //turn motor ON
    motors_ON = true;
  }
  else {                                   //if screen not touched
    digitalWrite(motor_pin, LOW);          //turn motor OFF
    motors_ON = false;

  }
}

//8===========================D

void fire() { //if motor byte on, turn motor on and check for time it has been on

  if (can_fire && !is_firing && motors_ON) {
    //if (can_fire && !is_firing) {
    firing_start_time = millis();
    recoil_start_time = millis();
    is_firing = true;
  }

  firing_current_time = millis();
  recoil_current_time = millis();

  if (is_firing && firing_current_time - firing_start_time < firing_time) {
    recoil_servo.write(recoil_pushed);
  }
  else if (is_firing && recoil_current_time - recoil_start_time < recoil_time) {
    recoil_servo.write(recoil_rest);
  }
  else if (is_firing && recoil_current_time - recoil_start_time > recoil_time) {
    is_firing = false;
  }

}