/// <summary>
/// Retrieves the spi bus. If the bus channel is not registered it sets it up automatically.
/// If it had been previously registered, then the bus is simply returned.
/// </summary>
/// <param name="channel">The channel.</param>
/// <param name="frequency">The frequency.</param>
/// <returns></returns>
internal static SpiChannel Retrieve(SpiChannelNumber channel, int frequency)
{
lock (SyncRoot)
{
if (Buses.ContainsKey(channel))
{
return(Buses[channel]);
}
var newBus = new SpiChannel(channel, frequency);
Buses[channel] = newBus;
return(newBus);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="SpiChannel"/> class.
/// </summary>
/// <param name="channel">The channel.</param>
/// <param name="frequency">The frequency.</param>
private SpiChannel(SpiChannelNumber channel, int frequency)
{
lock (SyncRoot)
{
Frequency = frequency.Clamp(MinFrequency, MaxFrequency);
Channel = (int)channel;
FileDescriptor = WiringPi.WiringPiSPISetup((int)channel, Frequency);
if (FileDescriptor < 0)
{
HardwareException.Throw(nameof(SpiChannel), channel.ToString());
}
}
}
