int in1=6;
int in2=9;
int in3=10;
int in4=11;
int ena=3;
int enb=5;
void setup() {
digitalWrite(in1‚OUTPUT);
digitalWrite(in2‚OUTPUT);
digitalWrite(in3‚OUTPUT);
digitalWrite(in4‚OUTPUT);
digitalWrite(enb‚OUTPUT);
digitalWrite(enb‚OUTPUT);
}
void loop() {
if(Serial.available()>0){
  data=Serial.read();
  if(data=='f'){
  forward();
  }
  if(data=='b'){
  backward();
  }
  if(data=='r'){
  turnright();
  }
  if(data=='l'){
  turnleft();
    }
    if(data=='s'){
      stop();
      }
      }
      }
      void forward(){
      analogWrite(ena‚220);
      analogWrite(enb‚220);
      digitalWrite(in1‚HIGH);
      digitalWrite(in2‚LOW);
      digitalWrite(in3‚HIGH);
      digitalWrite(in4‚LOW);
      }

      void backward(){
      analogWrite(ena‚110);
      analogWrite(enb‚110);
      digitalWrite(in1‚LOW);
      digitalWrite(in2‚HIGH);
      digitalWrite(in3‚LOW);
      digitalWrite(in4‚HIGH);
      }
      void turnright(){
      analogWrite(ena‚100);
      analogWrite(enb‚100);
      digitalWrite(in1‚LOW);
      digitalWrite(in2‚HIGH);
      digitalWrite(in3‚HIGH);
      digitalWrite(in4‚LOW);
      }
      void turnleft(){
      analogWrite(ena‚100);
      analogWrite(enb‚100);
      digitalWrite(in1‚HIGH);
      digitalWrite(in2‚LOW);
      digitalWrite(in3‚LOW);
      digitalWrite(in4‚HIGH);
      }
      void stop(){
      analogWrite(ena‚0);
      analogWrite(enb‚0);
      digitalWrite(in1‚LOW);
      digitalWrite(in2‚LOW);
      digitalWrite(in3‚LOW);
      digitalWrite(in4‚LOW);
      }