arduino BT+L9110

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 9); // RX, TX
const int AIA = 4;  // (pwm) pin 9 connected to pin A-IA
const int AIB = 5;  // (pwm) pin 5 connected to pin A-IB
const int BIA = 6; // (pwm) pin 10 connected to pin B-IA
const int BIB = 7;  // (pwm) pin 6 connected to pin B
byte speed=255;
void setup()
{

  pinMode(AIA, OUTPUT); // set pins to output
  pinMode(AIB, OUTPUT);
  pinMode(BIA, OUTPUT);
  pinMode(BIB, OUTPUT);
    pinMode(11,OUTPUT);
    pinMode(12,OUTPUT);
    digitalWrite(11,LOW);
    digitalWrite(12,HIGH);
   // Open serial communications and wait for port to open:
   Serial.begin(9600);
   Serial.println("TEST ARDUINO");
   // SoftwareSerial "com port" data rate. JY-MCU v1.03 defaults to 9600.
   mySerial.begin(9600);
   mySerial.println("Write something :");

}

String msg="",ordre="";
char c,cmd,cmdAct;
void loop()
{
   if(mySerial.available())
   {
    while(mySerial.available())
    {
      msg+=(char)mySerial.read();
      ordre=msg;


    }
     cmd = msg[11];   //direction
     cmdAct = msg[22];//command


   }
   if(ordre[22]=='1')
   {
      Serial.println("en cours");
    switch(cmd)
    {
      case 'a':
        Serial.println("forward");
        forward();

      break;
      case 'q':
        Serial.println("backward");
        backward();
      break;
      case 's':
        Serial.println("left");
        left();
      break;
      case 'r':
        Serial.println("right");
        right();
      break;
    }
   }
   else if(ordre[22]=='2')
   {
       Serial.println("stop");
       halt();
   }
   msg="";
}// END loop()

void halt()
{
  analogWrite(AIA, 0);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, 0);
}
void backward()
{
  analogWrite(AIA, 0);
  analogWrite(AIB, speed);
  analogWrite(BIA, 0);
  analogWrite(BIB, speed);
}

void forward()
{
  analogWrite(AIA, speed);
  analogWrite(AIB, 0);
  analogWrite(BIA, speed);
  analogWrite(BIB, 0);
}

void left()
{
  analogWrite(AIA, speed);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, speed);
}

void right()
{
  analogWrite(AIA, 0);
  analogWrite(AIB, speed);
  analogWrite(BIA, speed);
  analogWrite(BIB, 0);
}