Initialize Ultrasonic: takes no arguments, returns nothing
Initialize the lastRisingEdge and pulseWidth
Initialize the input capture to capture rising and falling edges
Initialize the output compare to have no pin connected and schedule the next rising edge
EnableInterrupts

ReturnUltrasonicDistance: takes no arguments, returns unsigned int distance in cm
The return signal period is 3/4 of the pulseWidth (750 kHz rate) divided by 2 (ultrasonic to target and back)
Convert high time to distance in cm
Return distance

OutputPulse (output compare)
If currently high and not waiting to relinquish control
	Lower line
	Set timer to wait to relinquish control
	Set relinquish control flag to true
Else if relinquish control flag is true
	Schedule next rising edge
	Change port to input
	Set relinquish control flag to false (released control to sensor)
Else
	Change port to input
	Raise line
	Schedule falling edge
Clear flag

InputPulse: (Input capture)
If currently high
	Record time as rising edge time
Else currently low
	subtract current time from rising edge time to get high time
	If the high time is greater than our PWM width, save it as pulseWidth (valid return signal)
Clear flag