  Two motors attached to the motor shield.
  speaker/piezo for sound
  
+ PIN ALLOCATION:
+ 
+ 13 - Motor B direction
+ 12 - Motor A direction
+ 11 - (blocked by shield)
+ 10 - Infrared remote receiver
+ 9  - Battery LED 1 (cut brake connect on bottom of the shield)
+ 8  - Battery LED 2 (cut brake connect on bottom of the shield)
+ 7  - Ping trigger
+ 6  - Motor B pwm
+ 5  - Motor A pwm
+ 4  - Ping echo
+ 3  - (blocked by shield)
+ 2  - Sound
+ 1  - not connected (Serial write)
+ 0  - not connected (Serial read)
+ 
+ A0 - Motor current sensor (not used)
+ A1 - Motor current sensor (not used)
+ A2 - Battery LED 3
+ A3 - unused
+ A4 - Thumbstick vertical
+ A5 - Thumbstick horizontal
+ 
+ 
+ ABOUT THE TIMERS:
+ 
  Arduino Uno has three timers; timer 0, timer 1, timer 2
  Timers can be used without their output going to the pins, the PWM pins.
 

 Timing functions we use:
 
  timer 0 - Arduino time functions; millis()
  timer 1 - Generates the tones for sound 
  timer 2 - Generates the pulses for driving the motors a varying speeds
  
 PWM (timer) pins we use:
  timer 0 pin 5  - Unused
  timer 0 pin 6  - Unused
  timer 1 pin 9  - Brake for motor A. Can only be used for digitalRead() & digitalWrite()
  timer 1 pin 10 - IR receiver.            Can only be used for digitalRead() & digitalWrite()
  timer 2 pin 3  - Motor A to control speed.
  timer 2 pin 11 - Motor B to control speed.
 
 Timer 0 is used by the arduino for millis().
 The motorshield uses timer 2, for pwm on pins 3 & 11.
 Since the standard arduino tone function uses timer 2 also, 
 we have to use a different library "NewTone" this uses timer 1 instead
 which means no pwm on pins 10 & 9. it also means it is incompatable with the 
 standard servo library.
 So we have pwm left on pins 5 & 6 to put some leds on.
 
 
 */


// without stopping everything for a delay.
#include "SimpleTimer.h"
#include <Servo.h>
#include "Sound.h"


