94 lines
3.6 KiB
C#
94 lines
3.6 KiB
C#
namespace Unosquare.RaspberryIO.Gpio
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{
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using Native;
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using Swan.Abstractions;
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using System.Collections.Generic;
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using System.Collections.ObjectModel;
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using System.Linq;
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/// <summary>
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/// A simple wrapper for the I2c bus on the Raspberry Pi
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/// </summary>
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public class I2CBus : SingletonBase<I2CBus>
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{
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// TODO: It would be nice to integrate i2c device detection.
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private static readonly object SyncRoot = new object();
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private readonly Dictionary<int, I2CDevice> _devices = new Dictionary<int, I2CDevice>();
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/// <summary>
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/// Prevents a default instance of the <see cref="I2CBus"/> class from being created.
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/// </summary>
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private I2CBus()
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{
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// placeholder
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}
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/// <summary>
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/// Gets the registered devices as a read only collection.
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/// </summary>
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public ReadOnlyCollection<I2CDevice> Devices => new ReadOnlyCollection<I2CDevice>(_devices.Values.ToArray());
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/// <summary>
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/// Gets the <see cref="I2CDevice"/> with the specified device identifier.
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/// </summary>
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/// <value>
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/// The <see cref="I2CDevice"/>.
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/// </value>
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/// <param name="deviceId">The device identifier.</param>
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/// <returns>A reference to an I2C device</returns>
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public I2CDevice this[int deviceId] => GetDeviceById(deviceId);
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/// <summary>
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/// Gets the device by identifier.
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/// </summary>
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/// <param name="deviceId">The device identifier.</param>
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/// <returns>The device reference</returns>
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public I2CDevice GetDeviceById(int deviceId)
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{
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lock (SyncRoot)
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{
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return _devices[deviceId];
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}
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}
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/// <summary>
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/// Adds a device to the bus by its Id. If the device is already registered it simply returns the existing device.
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/// </summary>
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/// <param name="deviceId">The device identifier.</param>
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/// <returns>The device reference</returns>
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/// <exception cref="KeyNotFoundException">When the device file descriptor is not found</exception>
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public I2CDevice AddDevice(int deviceId)
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{
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lock (SyncRoot)
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{
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if (_devices.ContainsKey(deviceId))
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return _devices[deviceId];
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var fileDescriptor = SetupFileDescriptor(deviceId);
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if (fileDescriptor < 0)
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throw new KeyNotFoundException($"Device with id {deviceId} could not be registered with the I2C bus. Error Code: {fileDescriptor}.");
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var device = new I2CDevice(deviceId, fileDescriptor);
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_devices[deviceId] = device;
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return device;
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}
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}
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/// <summary>
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/// This initializes the I2C system with your given device identifier.
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/// The ID is the I2C number of the device and you can use the i2cdetect program to find this out.
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/// wiringPiI2CSetup() will work out which revision Raspberry Pi you have and open the appropriate device in /dev.
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/// The return value is the standard Linux filehandle, or -1 if any error – in which case, you can consult errno as usual.
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/// </summary>
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/// <param name="deviceId">The device identifier.</param>
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/// <returns>The Linux file handle</returns>
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private static int SetupFileDescriptor(int deviceId)
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{
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lock (SyncRoot)
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{
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return WiringPi.WiringPiI2CSetup(deviceId);
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}
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}
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}
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}
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