  Two motors attached to the motor shield.
  speaker/piezo for sound
  
- Arduino Uno has three timers; timer 0, timer 1, timer 2,
+ 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.
+
+  timer 0 (controls pin 5, 6)  
+  timer 1 (controls pin 10, 9)
+  timer 2 (controls pin 3, 11) 
+  
+ 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 - Unused.            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, 

// although there is little point in doing so.
SimpleTimer timer;

// Creat the sound playing object.
Sound snd(sound_pin);

void setup() {
  Serial.begin(9600); // Open serial monitor at 9600 baud to see ping results.
  
  
  // Setup Channel A

 */

#include <util/delay.h>

#include <NewPing.h> // From https://code.google.com/p/arduino-new-ping/
#include <NewTone.h> // From https://code.google.com/p/arduino-new-tone/

