Pharmaceutical Vending Machine

char m; //Declare a variable to store signal
void setup() 
{
  // put your setup code here, to run once:
  Serial.begin(9600); //To access data exchange via bluetooth
  pinMode(9,OUTPUT); //Control left motor 
  pinMode(10,OUTPUT); //Control left motor
  pinMode(11,OUTPUT); //Control right motor
  pinMode(12,OUTPUT); //Control right motor
  
  //Initially both the motors are in stop position
  digitalWrite(10,LOW);
  digitalWrite(9,LOW);
  digitalWrite(11,LOW);
  digitalWrite(12,LOW);
  delay(2000);
}

void loop() 
{
   // Put your main code here, to run repeatedly:
   // while(!Serial.available())
   if(Serial.available()>0) //When signal begins
     {
       m=Serial.read(); //Read the signal
       if(m=='a') 
       {
          left(); //Jumps to the function 'left'
       }
    
       if(m=='b')
       {
          right(); //Jumps to the function 'right'
       }
       delay(200);
     }
}


void left()
{
      //Function left starts
      digitalWrite(9,LOW); //Left motor starts moving
      digitalWrite(10,HIGH); //Left motor starts moving
      digitalWrite(11,LOW); //Right motor is stationary
      digitalWrite(12,LOW); //Right motor is stationary
      delay(1250); //Duration of movement of left motor
      
      //Both the motors Come to stationary position
      digitalWrite(10,LOW);
      digitalWrite(9,LOW);
      digitalWrite(11,LOW);
      digitalWrite(12,LOW);
      delay(1000);
}

void right()
{
      digitalWrite(11,LOW); //Right motor starts moving
      digitalWrite(12,HIGH); //Right motor starts moving
      digitalWrite(10,LOW); //Left motor is stationary
      digitalWrite(9,LOW); //Left motor is stationary
      delay(650);

      //Both the motors Come to stationary position
      digitalWrite(10,LOW);
      digitalWrite(9,LOW);
      digitalWrite(11,LOW);
      digitalWrite(12,LOW);
      delay(1000);     
}