Integrating C#.NET with Embedded System.Chapter-4

SERIAL COMMUNICATION

In telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels.

Setting Up

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.IO.Ports

 using System.Windows.Forms;

System.IO.Ports is the class to use without resulting to low level hacking. This covers all the serial ports that appear on the machine.

SerialPort ComPort = newSerialPort();

This will create an object called ComPort. This will create a serial port object with the following parameters as default 9600bps, no parity, one stop bit and no flow control.

Shown below is the form:

 

This is standard Windows Forms Application via File menu. To this add the button (name Ports) and a Rich Text Box.The button is called btnGetSerialPorts and the Rich Text called as rtbIncomingData (the name will become apparent later).The rich text box is used as it is more flexible than the ordinary text box. Its uses for sorting and aligning text are considerably more than the straight textbox.

This shows all the devices that appear as com ports, a mistake to make is thinking that a device if plugged into the USB will appear as a COM Port.

The baud rate is the amount of possible events that can happen in a second. It is displays usually as a number of bit per second, the possible number that can be used are 300, 600, 1200, 2400, 9600, 14400, 19200, 38400, 57600, and 115200 (these come from the UAR 8250 chip is used, if a 16650 the additional rates of 230400, 460800 and 921600) .

The next box is the number of Data bits, these represent the total number of transitions of the data transmission (or Tx line) 8 is the standard ( 8 is useful for reading certain embedded application as it gives two nibbles (4 bit sequences).

The Handshaking property is used when a full set of connections are used (such as the grey 9 way D-types that litter my desk). It was used originally to ensure both ends lined up with each other and the data was sent and received properly. A common handshake was required between both sender and receiver. Below is the code for the combo box:

Here is the complete code for serial communication between transmitter and receiver.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.IO.Ports;

using System.Windows.Forms;

namespace CodeProjectSerialComms
    {
       SerialPort ComPort = newSerialPort();
       internaldelegatevoidSerialDataReceivedEventHandlerDelegate(object sender, SerialDataReceivedEventArgs );
       internaldelegatevoidSerialPinChangedEventHandlerDelegate(object sender, SerialPinChangedEventArgs e);
    privateSerialPinChangedEventHandler SerialPinChangedEventHandler1;
    delegatevoidSetTextCallback(string text);
    string InputData = String.Empty;

public Form1()
        {
            InitializeComponent();
            SerialPinChangedEventHandler1 = newSerialPinChangedEventHandler(PinChanged);
            ComPort.DataReceived += new System.IO.Ports.SerialDataReceivedEventHandler(port_DataReceived_1);
        }

privatevoid btnGetSerialPorts_Click(object sender, EventArgs e)
        {
string[] ArrayComPortsNames = null;
int index = -1;
string ComPortName = null;

//Com Ports
            ArrayComPortsNames = SerialPort.GetPortNames();
do
            {
                index += 1;
                cboPorts.Items.Add(ArrayComPortsNames[index]);


  }while(!((ArrayComPortsNames[index]==ComPortName)||(index == ArrayComPortsNames.GetUpperBound(0))));
Array.Sort(ArrayComPortsNames);

if (index == ArrayComPortsNames.GetUpperBound(0))

            {

                ComPortName = ArrayComPortsNames[0];

            }

//get first item print in text

            cboPorts.Text = ArrayComPortsNames[0];

//Baud Rate

            cboBaudRate.Items.Add(300);

            cboBaudRate.Items.Add(600);

            cboBaudRate.Items.Add(1200);

            cboBaudRate.Items.Add(2400);

            cboBaudRate.Items.Add(9600);

            cboBaudRate.Items.Add(14400);

            cboBaudRate.Items.Add(19200);

            cboBaudRate.Items.Add(38400);

            cboBaudRate.Items.Add(57600);

            cboBaudRate.Items.Add(115200);

            cboBaudRate.Items.ToString();

//get first item print in text

            cboBaudRate.Text = cboBaudRate.Items[0].ToString();

//Data Bits

            cboDataBits.Items.Add(7);

            cboDataBits.Items.Add(8);

//get the first item print it in the text

            cboDataBits.Text = cboDataBits.Items[0].ToString();

//Stop Bits

            cboStopBits.Items.Add("One");

            cboStopBits.Items.Add("OnePointFive");

            cboStopBits.Items.Add("Two");

//get the first item print in the text

            cboStopBits.Text = cboStopBits.Items[0].ToString();

//Parity

            cboParity.Items.Add("None");

            cboParity.Items.Add("Even");

            cboParity.Items.Add("Mark");

            cboParity.Items.Add("Odd");

            cboParity.Items.Add("Space");

//get the first item print in the text

            cboParity.Text = cboParity.Items[0].ToString();

//Handshake

            cboHandShaking.Items.Add("None");

            cboHandShaking.Items.Add("XOnXOff");

            cboHandShaking.Items.Add("RequestToSend");

            cboHandShaking.Items.Add("RequestToSendXOnXOff");

//get the first item print it in the text

            cboHandShaking.Text = cboHandShaking.Items[0].ToString();

        }

privatevoid port_DataReceived_1(object sender, SerialDataReceivedEventArgs e)

        {

            InputData = ComPort.ReadExisting();

if (InputData != String.Empty)

            {

this.BeginInvoke(newSetTextCallback(SetText), newobject[] { InputData });

            }

        }

privatevoid SetText(string text)

        {

this.rtbIncoming.Text += text;

        }

privatevoid btnPortState_Click(object sender, EventArgs e)

        {

if (btnPortState.Text == "Closed")

            {

                btnPortState.Text = "Open";

                ComPort.PortName = Convert.ToString(cboPorts.Text);

                ComPort.BaudRate = Convert.ToInt32(cboBaudRate.Text);

                ComPort.DataBits = Convert.ToInt16(cboDataBits.Text);

                ComPort.StopBits = (StopBits)Enum.Parse(typeof(StopBits), cboStopBits.Text);

                ComPort.Handshake = (Handshake)Enum.Parse(typeof(Handshake), cboHandShaking.Text);

                ComPort.Parity = (Parity)Enum.Parse(typeof(Parity), cboParity.Text);

                ComPort.Open();

            }

elseif (btnPortState.Text == "Open")

            {

                btnPortState.Text = "Closed";

                ComPort.Close();

            }

        }

privatevoid rtbOutgoing_KeyPress(object sender, KeyPressEventArgs e)

        {

if (e.KeyChar == (char)13) // enter key 

            {

                ComPort.Write("\r\n");

                rtbOutgoing.Text = "";

            }

elseif (e.KeyChar < 32 || e.KeyChar > 126)

            {

                e.Handled = true; // ignores anything else outside printable ASCII range 

            }

else

            {

                ComPort.Write(e.KeyChar.ToString());

            }

        }

privatevoid btnHello_Click(object sender, EventArgs e)

        {

            ComPort.Write("Hello World!");

        }

    }

OUTPUT: