how to send "1" to a serial port and then receive the values the pic will be sending me after it received "1"

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can i write a byte to the serial port and then read the values it 'll send me ?
i want to be able to write to the serial port "1"
and when my pic micro controller receives this "1" it will sends me the values of portD in which i want to use later

but i 'm not able to communicate correctly with the serial port

this is not the program i'm trying to build but i' just testing the basics on how to read and write from/to a serial port and nothing is working so far :/

i'm just testing how to communicate with the serial port and this is the code i'm trying

i have a button that when i click i want a "1" to be sent and then the textbox1 will display the value received

SerialPort serialPort1 = new SerialPort("COM2", 300, Parity.None, 8, StopBits.One);
        
        private void button1_Click(object sender, EventArgs e)
        {
            serialPort1.Open();
            serialPort1.Write("1");
            serialPort1.Close();

            if (serialPort1.IsOpen)
            {
                serialPort1.Close();
                serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived);
                serialPort1.Open();

            }
            else
            {
                serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived);
                serialPort1.Open(); //opens the port
            }

        }
        int rs;

        private void serialPort1_DataReceived(object sender,SerialDataReceivedEventArgs e)
        {
            SerialPort serialPort1=(SerialPort)sender;
            try
            {

                rs = serialPort1.ReadByte();
                this.Invoke(new EventHandler(type));
            }
            catch (System.TimeoutException)
            {
            }


        }
        private void type(object s,EventArgs e)
        {
            textBox1.Text = rs.ToString();
        }

Posted 2-May-14 2:12am

Duaa7

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OriginalGriff · Accepted Answer · 2014-05-02T02:39:00

Solution 1

Firstly, stop opening and closing the port: it won't help and it may cause data to be lost. While the port is closed, anything received by the physical port will be thrown away...and it allows other applications to "grab" the port as well. And you don't need an event handler to pass the data either.

So open the port once, add the DataReceived handler once, and send the data.
Then use the event to fetch all the data the PIC returns, and display it - but don't use an int to transfer it, as the RX thread could easily overwrite it before your UI thread gets a chance to read it and display it. Instead, read all the bytes in one go, and pass the data through to the UI thread via a Invoke method call:

C#

string data = SerialPort1.ReadExisting();
Invoke(new MethodInvoker(() => { ShowData(data);}));

C#

private void ShowData(string s)
   {
   textBox1.Text += s;
   }

Posted 2-May-14 2:39am

OriginalGriff

Comments

Duaa7 2-May-14 12:03pm

i'm not sure i can write and then read from the port and i'm not able to

Duaa7 2-May-14 12:04pm

private void button1_Click(object sender, EventArgs e)
{

serialPort1.Write("1"); // there's an exception that's unhandled in this line
serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived);
serialPort1.Open(); //opens the port

}

private void serialPort1_DataReceived(object sender,SerialDataReceivedEventArgs e)
{
SerialPort serialPort1=(SerialPort)sender;
string data = serialPort1.ReadExisting();
Invoke(new MethodInvoker(() => { ShowData(data); }));

}
//even this isn't working so i think i can't write and directly read afterwards or am i wrong?

OriginalGriff 2-May-14 12:07pm

You're wrong! Trust me - you can use the same port for reading and writing at the same time.

Check your connections with Hyperterminal or similar, and make sure it all works to your PIC first, then copy the settings into your code and try there.
One variable at a time: it could be as simple as you plugged the connector in wrong! :laugh:

OriginalGriff 2-May-14 12:09pm

Sorry - just saw your bit at the top - you can't write to a closed port.
Move the serialPort1.Open and the DataReceived event handler out of the button click event, and into the form load. You only want to execute each of them once, ever.

Duaa7 2-May-14 12:38pm

alright thank you for the info :), and sorry for my lack of knowledge i'm new to this ,and i have nothing but the internet to get the help i need.

Duaa7 2-May-14 12:49pm

the problem is that i have to write "1" and send it to the pic so that the pic would send me the output's values ,my assembly program works like : whenever a "1" is sent the microcontroller will start sending the values via tx and once "0" is sent it will set the outputs to 0,and i have no idea how will i translate that to c# code

OriginalGriff 2-May-14 14:04pm

So start by testing the assembly code: use software you know works (Hyperterminal will do) and send the data from the keyboard. Does it do exactly what you expect?
If so, you can move on. But trying to test unknown software with unknown software? Thats a recipe for guesses, mistakes, and fixing the wrong code! :laugh:

Duaa7 2-May-14 14:35pm

i'm using proteus to stimulate the circuit,the assembly so far is good it does what it have to on the circuit but i need to see the value its sending to the serial port, and i can't see that anywhere

OriginalGriff 2-May-14 14:50pm

If you can't see it anywhere that that's your first problem.
Until you sort that out, you can't see anything - and you can't debug anything.
So start with "simple" assembly code, and send a single character over and over again: '3' is a good choice as it's nice and easy to see on a scope if you need to: Binary 01010101 with some parity/start/stop bits makes it easy to time and make sure that the TX speed and other settings are is what you think they should be.

Duaa7 4-May-14 6:01am

thank you :), everything is working now.

OriginalGriff 4-May-14 6:06am

You're welcome!