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4.1 Cosine generator lab (Page 2/2)

Part 2

In this part you will be creating a Visual Basic (VB) application that communicates with a target application through the Real Time Data Exchange (RTDX). The VB application will have two buttons that when pressed will send different numbers to the target (DSP board). The target application will print the value received to a LOG object and turn the output cosine either on or off.
Create a new Visual Basic project (These may not be exactly the steps depending on your version of Visual Studio):

Start Visual Studio.
Select Create Project.
In the Project types: select Visual Basic:Windows.
Under Templates: select Windows Forms Application.
The Solution Name will be CosineOnOff .
Click OK.

Add two buttons to your form with the following characteristics:

(Name): Button1
Text: On
(Name): Button2
Text: Off

In the Form code in the Form1:(Declarations) section add code for the status constants and other variables. This will be right under the statement Public Class Form1 . The code should be:

'--------------------------------------------------------------------------
    ' RTDX Return Status'--------------------------------------------------------------------------
    Const Success =&H0 ' Method call is valid
    Const Failure =&H80004005 ' Method call failed
    Const ENoDataAvailable =&H8003001E ' No data currently available.
    Const EEndOfLogFile =&H80030002 ' End of transmission'--------------------------------------------------------------------------
    ' Variable Declarations'--------------------------------------------------------------------------
    Dim rtdx As Object ' Holds the rtdx objectDim bufferstate As Integer ' Holds the number of bytes xmitted
    ' or pending xmissionDim status As Integer ' RTDX Function call return status

The first function to be executed when a project is started is Form:Load . In this function put the code for initializing the RTDX channel. Name the channel HtoTchan for Host to Target channel.

Try
        rtdx_out = CreateObject("RTDX")    status = rtdx.Open("HtoTchan", "W") ' Open channel for writing
    Catch ex As Exception    'Exception occured when opening the RTDX object
        System.Diagnostics.Debug.WriteLine("Opening of channel HtoTchan failed")    rtdx_out = Nothing
        End ' Force program terminationEnd Try

One of the last functions to execute is the Form:FormClosing function. In this function put the code for cleaning things up.

status = rtdx.Close() ' Close rtdx
    Set rtdx = Nothing ' Free memory reserved for rtdx obj

In the Button1:Click function put the code to be executed when the button is clicked. When the button is clicked it should send a 4 byte integer, the number 1, to the target indicating that button 1 was clicked. The code for doing this is:

Dim Data As IntegerData = 1
    status = rtdx.WriteI4(Data, bufferstate)If status = Success ThenDebug.Print "Value "&Data&" was sent to the target"
    ElseDebug.Print "WriteI4 failed"
    End If

In the Button2:Click function put the code to be executed when the button is clicked. When the button is clicked it should send a 4 byte integer, the number 0, to the target indicating that button 2 was clicked. The code is the same as above, the data is just 0.
Now the target code needs to be updated.
Save the DSK6713_audio.c file as DSK6713_audio2.c and use this as the main file in your project.
Include a header file so we can use the RTDX.

#include<rtdx.h>

Create a global input channel called HtoTchan . This code will go in the global variables section.

RTDX_CreateInputChannel( HtoTchan );

Add code to the top of function processing :

int data;
    int status;int busystatus=0;/* enable the Host to Target channel */
    RTDX_enableInput(&HtoTchan );

In the while loop add the code:

/* check to see if the channel is busy before the read */
    if (busystatus == 0){
    /* Print the data if something was actually read */if (RTDX_sizeofInput(&HtoTchan) == sizeof(data))
    {// data received here
    LOG_printf(&trace,"Value sent = %d",data);
    }status = RTDX_readNB(&HtoTchan,&data, sizeof(data) );
    }/* get the status of the channel */busystatus = RTDX_channelBusy(&HtoTchan);

The above code will read 4 byte values from the HtoTchan input channel. When a value is received the program will get to the statement // data received here and will have the value in the variable data .
Since the variable data will contain either a 1 or a 0 this can be used to multiply the cosine value to turn it on and off. (Int16)(32000.0*y*data);
Set up RTDX by opening the Configuration window with Tools->RTDX->Configuration Control, right click to select properties and then click on Continuous mode. After closing the properties check the Enable RTDX box.
Run the target application. It is important that the target application be started before the VB application. If the VB application is started first the channel may not get initialized.
Run the VB application.
Verify that the tone that is output can be turned on and off with your VB program.

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Read also:

OpenStax, Dsp lab with ti c6x dsp and c6713 dsk. OpenStax CNX. Feb 18, 2013 Download for free at http://cnx.org/content/col11264/1.6

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