   mma.getEvent(&event);
   
   lcd.clear();
-
-  lcd.print("Revolutions: ");
   
-  lcd.print(tickCount); 
+  kph = calculateKPH();
+  
+  lcd.print("Spd: ");
+  lcd.print(kph);
+  lcd.print("kph");
   
   lcd.setCursor(0,1);
   lcd.print("AccY:");
   lcd.print(event.acceleration.y);
   lcd.print(" m/s^2");
+  
   // using blocking delay debounces the accelerometer and gives the display time to refresh
   delay(250);
 }

#include <Adafruit_MMA8451.h>
#include <Adafruit_Sensor.h>

// Hall effect sensor read pin, make it an interrupt pin so we catch all revolutions
const byte HALL_SENSOR = 2;
boolean isHallSensorTriggered = false;
int tickCount = 0;
int millisSinceLastTick = 0;

// 16x2 LCD display pins

  millisSinceLastTick = millis();
}

// ******************* INTERRUPT EVENTS *******************

double calculateKPH() {
  // How many CM per second we've traveled, based on wheel circumference and number of wheel turns since last check
  double cmps =  (1000/(millisSinceLastTick - currentMillis)) * WHEEL_CIRCUMFERENCE * tickCount;
  // reset counts
  tickCount = 0;
  currentMillis = millisSinceLastTick;
  return cmps/10000 *360;
}
