   inputString.reserve(200);
   
   pinMode(LED_PIN, OUTPUT);
+  
+  // Left motor power wiring is reversed.
+  motors.flipLeftMotor(true);
+  
+  // Initial speed is zero
   motors.setLeftSpeed(0);
   motors.setRightSpeed(0);
 }

//#include <ZumoMotors.h>

#define LED_PIN 13

//ZumoMotors motors;

String inputString = "";         // a string to hold incoming data
boolean stringComplete = false;  // whether the string is complete

 response.  Multiple bytes of data may be available.
 */
void serialEvent() {
  int vel, vel2, dt;
  while (Serial.available()) {
    // Get state character from buffer
    char c = (char)Serial.read();
