The SerialPortManager.cs file contains a snippet of a singleton class implemented in .NET C#, which I created and utilized in various .NET projects to manage serial data communication, particularly for projects involving interaction with an Arduino board. This class serves as a wrapper built on top of the System.IO.Ports.SerialPort class. The following code snippet is also available on Gist.
The code snippet
/*
MIT License
Copyright (c) 2016 Heiswayi Nrird
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
using System;
using System.IO;
using System.IO.Ports;
using System.Threading;
namespace HeiswayiNrird.Singletons
{
public sealed class SerialPortManager
{
private static readonly Lazy<SerialPortManager> lazy = new Lazy<SerialPortManager>(() => new SerialPortManager());
public static SerialPortManager Instance { get { return lazy.Value; } }
private SerialPort _serialPort;
private Thread _readThread;
private volatile bool _keepReading;
private SerialPortManager()
{
_serialPort = new SerialPort();
_readThread = null;
_keepReading = false;
}
/// <summary>
/// Update the serial port status to the event subscriber
/// </summary>
public event EventHandler<string> OnStatusChanged;
/// <summary>
/// Update received data from the serial port to the event subscriber
/// </summary>
public event EventHandler<string> OnDataReceived;
/// <summary>
/// Update TRUE/FALSE for the serial port connection to the event subscriber
/// </summary>
public event EventHandler<bool> OnSerialPortOpened;
/// <summary>
/// Return TRUE if the serial port is currently connected
/// </summary>
public bool IsOpen { get { return _serialPort.IsOpen; } }
/// <summary>
/// Open the serial port connection using basic serial port settings
/// </summary>
/// <param name="portname">COM1 / COM3 / COM4 / etc.</param>
/// <param name="baudrate">0 / 100 / 300 / 600 / 1200 / 2400 / 4800 / 9600 / 14400 / 19200 / 38400 / 56000 / 57600 / 115200 / 128000 / 256000</param>
/// <param name="parity">None / Odd / Even / Mark / Space</param>
/// <param name="databits">5 / 6 / 7 / 8</param>
/// <param name="stopbits">None / One / Two / OnePointFive</param>
/// <param name="handshake">None / XOnXOff / RequestToSend / RequestToSendXOnXOff</param>
public void Open(
string portname = "COM1",
int baudrate = 9600,
Parity parity = Parity.None,
int databits = 8,
StopBits stopbits = StopBits.One,
Handshake handshake = Handshake.None)
{
Close();
try
{
_serialPort.PortName = portname;
_serialPort.BaudRate = baudrate;
_serialPort.Parity = parity;
_serialPort.DataBits = databits;
_serialPort.StopBits = stopbits;
_serialPort.Handshake = handshake;
_serialPort.ReadTimeout = 50;
_serialPort.WriteTimeout = 50;
_serialPort.Open();
StartReading();
}
catch (IOException)
{
if (OnStatusChanged != null)
OnStatusChanged(this, string.Format("{0} does not exist.", portname));
}
catch (UnauthorizedAccessException)
{
if (OnStatusChanged != null)
OnStatusChanged(this, string.Format("{0} already in use.", portname));
}
catch (Exception ex)
{
if (OnStatusChanged != null)
OnStatusChanged(this, "Error: " + ex.Message);
}
if (_serialPort.IsOpen)
{
string sb = StopBits.None.ToString().Substring(0, 1);
switch (_serialPort.StopBits)
{
case StopBits.One:
sb = "1"; break;
case StopBits.OnePointFive:
sb = "1.5"; break;
case StopBits.Two:
sb = "2"; break;
default:
break;
}
string p = _serialPort.Parity.ToString().Substring(0, 1);
string hs = _serialPort.Handshake == Handshake.None ? "No Handshake" : _serialPort.Handshake.ToString();
if (OnStatusChanged != null)
OnStatusChanged(this, string.Format(
"Connected to {0}: {1} bps, {2}{3}{4}, {5}.",
_serialPort.PortName,
_serialPort.BaudRate,
_serialPort.DataBits,
p,
sb,
hs));
if (OnSerialPortOpened != null)
OnSerialPortOpened(this, true);
}
else
{
if (OnStatusChanged != null)
OnStatusChanged(this, string.Format(
"{0} already in use.",
portname));
if (OnSerialPortOpened != null)
OnSerialPortOpened(this, false);
}
}
/// <summary>
/// Close the serial port connection
/// </summary>
public void Close()
{
StopReading();
_serialPort.Close();
if (OnStatusChanged != null)
OnStatusChanged(this, "Connection closed.");
if (OnSerialPortOpened != null)
OnSerialPortOpened(this, false);
}
/// <summary>
/// Send/write string to the serial port
/// </summary>
/// <param name="message"></param>
public void SendString(string message)
{
if (_serialPort.IsOpen)
{
try
{
_serialPort.Write(message);
if (OnStatusChanged != null)
OnStatusChanged(this, string.Format(
"Message sent: {0}",
message));
}
catch (Exception ex)
{
if (OnStatusChanged != null)
OnStatusChanged(this, string.Format(
"Failed to send string: {0}",
ex.Message));
}
}
}
private void StartReading()
{
if (!_keepReading)
{
_keepReading = true;
_readThread = new Thread(ReadPort);
_readThread.Start();
}
}
private void StopReading()
{
if (_keepReading)
{
_keepReading = false;
_readThread.Join();
_readThread = null;
}
}
private void ReadPort()
{
while (_keepReading)
{
if (_serialPort.IsOpen)
{
//byte[] readBuffer = new byte[_serialPort.ReadBufferSize + 1];
try
{
//int count = _serialPort.Read(readBuffer, 0, _serialPort.ReadBufferSize);
//string data = Encoding.ASCII.GetString(readBuffer, 0, count);
string data = _serialPort.ReadLine();
if (OnDataReceived != null)
OnDataReceived(this, data);
}
catch (TimeoutException) { }
}
else
{
TimeSpan waitTime = new TimeSpan(0, 0, 0, 0, 50);
Thread.Sleep(waitTime);
}
}
}
}
}
Example on how to use it
An event named OnDataReceived is available for subscription to retrieve data.
Example:
using HeiswayiNrird.Singletons;
using System.Windows;
namespace SerialPortExample
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
// Subscribe to the event
SerialPortManager.Instance.OnDataReceived += Handler_OnDataReceived;
}
// Event handler
private void Handler_OnDataReceived(object sender, string data)
{
// TODO
// Process your 'data' here...
}
}
}
Alternatively, you can use an anonymous function and marshal it to the main UI thread.
Example:
using HeiswayiNrird.Singletons;
using System;
using System.Windows;
namespace SerialPortExample
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
// Subscribe to the event
SerialPortManager.Instance.OnDataReceived += (sender, data) =>
{
// TODO
// Process your 'data' here...
double value = Convert.ToDouble(incomingData); // Assuming the 'data' contains value "123"...
// Update the value to UI component...
Application.Current.Dispatcher.BeginInvoke(new Action(() =>
{
BindingTextBoxValue = value;
}));
};
}
// Binding properties
public double BindingTextBoxValue { get; set; }
}
}
Opening and closing the serial port connection
Example:
// To open/start the serial port on COM4 with 9600 bps
SerialPortManager.Instance.Open("COM4", 9600);
// To close/stop the serial port on COM4
SerialPortManager.Instance.Close();
Events to subscribe:
OnStatusChanged- to receive status messages.OnSerialPortOpened- to determine if the serial port is opened or not.
Example:
using HeiswayiNrird.Singletons;
using System.Windows;
namespace SerialPortExample
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
// Subscribe to the event
SerialPortManager.Instance.OnStatusChanged += (sender, status) =>
{
// Update connection status message to UI component
ConnectionStatus = status;
};
}
// Binding properties
public string ConnectionStatus { get; set; }
}
}
How this class avoids the deadlock issue
The SerialPortManager class utilizes the ReadPort() method to run on a separate thread and employs a while loop to acquire or read data from the serial port. When the SerialPortManager.Instance.Close() method is invoked, the _keepReading variable is set to false, halting the UI from receiving and updating data while waiting for the thread to fully terminate.
Directly calling System.IO.Ports.SerialPort.Close() on the UI thread to stop acquiring/reading data is avoided, as it could lead to a deadlock issue or application hang due to the serial port base stream being locked while handling serial port events.