/// <summary>
/// Initializes a new instance of the <see cref="ProximitySensor"/> class
/// </summary>
/// <param name="proximitySensorType">
/// </param>
/// <param name="analogInput">
/// The analog input to which the proximity sensor is attached
/// </param>
/// <exception cref="ArgumentNullException">
/// Thrown when the given <see cref="AnalogInput"/> is null
/// </exception>
/// <remarks>
/// This sensor is only provides valid results for objects farther than 3" away or objects closer than
/// <see cref="MaximumReadableDistance"/> from the sensor. Passing a trigger which attempts to obtain
/// distances outside of this range will result in a large number of false positives.
/// </remarks>
public ProximitySensor(ProximitySensorType proximitySensorType, AnalogInput analogInput)
{
if (analogInput == null)
{
throw new ArgumentNullException("analogInput");
}
this.proximitySensorType = proximitySensorType;
MaximumReadableDistance = GetMaximumReadableDistance(analogInput);
new Thread(() =>
{
while (true)
{
if (IsEnabled && ObjectDetectionTrigger != null)
{
var distance = new Distance(analogInput.ReadRaw(), proximitySensorType);
if (ObjectDetectionTrigger(MaximumReadableDistance, distance))
{
if (ObjectDetected != null)
{
ObjectDetected(this, new ObjectDetectedEventArgs(distance, DateTime.UtcNow));
}
}
}
Thread.Sleep(10);
}
}).Start();
}
/// <summary>
/// Converts an analog voltage output from a proximity sensor to a distance in centimeters
/// </summary>
/// <param name="analogVoltage">
/// An analog voltage output from a proximity sensor
/// </param>
/// <param name="proximitySensorType">
/// The type of Sharp proximity sensor being used
/// </param>
/// <returns>
/// The distance an object lies from the proximity sensor measured in centimeters
/// </returns>
public static double ToCentimeters(double analogVoltage, ProximitySensorType proximitySensorType)
{
double distance = 0;
switch (proximitySensorType)
{
case ProximitySensorType.GP2Y0A21YK:
distance = 41.543 * Math.Pow(analogVoltage + 0.30221, -1.5281);;
break;
case ProximitySensorType.GP2Y0A02YK0F:
distance = 61.681 * Math.Pow(analogVoltage, -1.133);
break;
}
return distance;
}
/// <summary>
/// Converts an analog voltage output from a proximity sensor to a distance in inches
/// </summary>
/// <param name="analogVoltage">
/// An analog voltage output from a proximity sensor
/// </param>
/// <param name="proximitySensorType">
/// The type of Sharp proximity sensor being used
/// </param>
/// <returns>
/// The distance an object lies from the proximity sensor measured in inches
/// </returns>
public static double ToInches(double analogVoltage, ProximitySensorType proximitySensorType)
{
return ToCentimeters(analogVoltage, proximitySensorType) / 2.54;
}
/// <summary>
/// Initializes a new instance of the <see cref="Distance"/> class
/// </summary>
/// <param name="digitalVoltage">
/// The digital output voltage from the proximity sensor
/// </param>
/// <param name="proximitySensorType">
/// The type of Sharp proximity sensor being used
/// </param>
internal Distance(int digitalVoltage, ProximitySensorType proximitySensorType)
{
analogVoltage = AdcHelper.ToAnalogVoltage(digitalVoltage);
this.digitalVoltage = digitalVoltage;
this.proximitySensorType = proximitySensorType;
}
