Como fiz um snowblower 3.0 com controle Bluetooth a partir de um smartphone Android

#include <SoftwareSerial.h>
#define BRAKEVCC 0
#define CW   1
#define CCW  2
#define BRAKEGND 3
#define CS_THRESHOLD 100

int inApin[2] = {7, 4};  // INA: Clockwise input
int inBpin[2] = {8, 9}; // INB: Counter-clockwise input
int pwmpin[2] = {5, 6}; // PWM input

int statpin = 10;

SoftwareSerial mySerial(2, 3); // RX, TX
char a,b;

void setup()  
{
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }


 pinMode(statpin, OUTPUT);

  // Initialize digital pins as outputs
  for (int i=0; i<2; i++)
  {
    pinMode(inApin[i], OUTPUT);
    pinMode(inBpin[i], OUTPUT);
    pinMode(pwmpin[i], OUTPUT);
  }
  // Initialize braked
  for (int i=0; i<2; i++)
  {
    digitalWrite(inApin[i], LOW);
    digitalWrite(inBpin[i], LOW);
  }

  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
  mySerial.println("Hello, world?");
}

void loop() // run over and over
{
    digitalWrite(statpin, HIGH);
    
  if (mySerial.available()){
        a=mySerial.read();

    if(a=='F'){
  motorGo(0, CW, 1023);
  motorGo(1, CW, 1023);
    }
    if(a=='B'){
  motorGo(0, CCW, 1023);
  motorGo(1, CCW, 1023);
    }
    if(a=='L'){
  motorGo(0, CW, 1023);
  motorGo(1, CCW, 1023);
    }
    if(a=='R'){
  motorGo(0, CCW, 1023);
  motorGo(1, CW, 1023);
    }
     if(a=='I'){
  motorGo(0, CW, 500);
  motorGo(1, CW, 1023);
    }
    if(a=='G'){
  motorGo(0, CW, 1023);
  motorGo(1, CW, 500);
    }
    if(a=='H'){
  motorGo(0, CCW, 1023);
  motorGo(1, CCW, 500);
    }
    if(a=='J'){
  motorGo(0, CCW, 500);
  motorGo(1, CCW, 1023);
    }
       if(a=='S'){
  motorOff(1);
  motorOff(2);
    }

    Serial.write(a);
    }else{
      
    }
  
}


void motorOff(int motor)
{
  // Initialize braked
  for (int i=0; i<2; i++)
  {
    digitalWrite(inApin[i], LOW);
    digitalWrite(inBpin[i], LOW);
  }
  analogWrite(pwmpin[motor], 0);
}

void motorGo(uint8_t motor, uint8_t direct, uint8_t pwm)
{
  if (motor <= 1)
  {
    if (direct <=4)
    {
      // Set inA[motor]
      if (direct <=1)
        digitalWrite(inApin[motor], HIGH);
      else
        digitalWrite(inApin[motor], LOW);

      // Set inB[motor]
      if ((direct==0)||(direct==2))
        digitalWrite(inBpin[motor], HIGH);
      else
        digitalWrite(inBpin[motor], LOW);

      analogWrite(pwmpin[motor], pwm);
    }
  }
}