/// <summary>
/// Called when a single infrared sensor pulse becomes available.
/// </summary>
/// <param name="pulse">The pulse.</param>
private void OnInfraredSensorPulseAvailable(InfraRedPulse pulse)
{
PulseAvailable?.Invoke(this, new InfraRedSensorPulseEventArgs(pulse));
}
/// <summary>
/// Initializes a new instance of the <see cref="InfraRedSensorPulseEventArgs" /> class.
/// </summary>
/// <param name="pulse">The pulse.</param>
internal InfraRedSensorPulseEventArgs(InfraRedPulse pulse)
: base()
{
Value = pulse.Value;
DurationUsecs = pulse.DurationUsecs;
}
/// <summary>
/// Reads the interrupt do work.
/// </summary>
private void ReadInterruptDoWork()
{
// Define some constants
const long GapUsecs = 5000;
const long MaxElapsedMicroseconds = 250000;
const long MinElapsedMicroseconds = 50;
const int IdleCheckIntervalMilliSecs = 32;
const int MaxPulseCount = 128;
// Setup the input pin
InputPin.PinMode = GpioPinDriveMode.Input;
InputPin.InputPullMode = GpioPinResistorPullMode.PullUp;
// Get the timers started!
var pulseTimer = new Native.HighResolutionTimer();
var idleTimer = new Native.HighResolutionTimer();
var pulseBuffer = new List <InfraRedPulse>(MaxPulseCount);
var syncLock = new object();
var idleChecker = default(Timer);
idleChecker = new Timer((s) =>
{
if (IsInReadInterrupt)
{
return;
}
lock (syncLock)
{
if (idleTimer.ElapsedMicroseconds < GapUsecs || idleTimer.IsRunning == false || pulseBuffer.Count <= 0)
{
return;
}
OnInfraredSensorRawDataAvailable(pulseBuffer.ToArray(), ReceiverFlushReason.Idle);
pulseBuffer.Clear();
idleTimer.Reset();
}
});
InputPin.RegisterInterruptCallback(EdgeDetection.RisingAndFallingEdges, () =>
{
IsInReadInterrupt = true;
lock (syncLock)
{
idleTimer.Restart();
idleChecker.Change(IdleCheckIntervalMilliSecs, IdleCheckIntervalMilliSecs);
var currentLength = pulseTimer.ElapsedMicroseconds;
var currentValue = InputPin.Read();
var pulse = new InfraRedPulse(currentValue, currentLength.Clamp(MinElapsedMicroseconds, MaxElapsedMicroseconds));
// Restart for the next bit coming in
pulseTimer.Restart();
// Do not add an idling pulse
if (pulse.DurationUsecs < MaxElapsedMicroseconds)
{
pulseBuffer.Add(pulse);
OnInfraredSensorPulseAvailable(pulse);
}
if (pulseBuffer.Count >= MaxPulseCount)
{
OnInfraredSensorRawDataAvailable(pulseBuffer.ToArray(), ReceiverFlushReason.Overflow);
pulseBuffer.Clear();
}
}
IsInReadInterrupt = false;
});
// Get the timers started
pulseTimer.Start();
idleTimer.Start();
idleChecker.Change(0, IdleCheckIntervalMilliSecs);
}
