MATLAB Link for Code Composer Studio Development Tools

Closing the Links or Cleaning Up

One of the most important programmatic processes you should do in every RTDX session is to clean up at the end. Cleaning up includes stopping your target processor, disabling the RTDX channels you enabled, disabling RTDX and closing your open channels. Performing this series of tasks ensures that future processes avoid trouble caused by unexpected interactions with left-over handles, channels, and links from your earlier development work. Best practices suggest that you include the following tasks (or an appropriate subset that meets your development needs) in your development scripts and programs.

We use four functions in this section; each has a purpose--the operational details in the following list explain how and why we use each one. They are

• clear--remove all RTDX objects and handles associated with a CCS and RTDX link. When you finish a session with RTDX, clear removes all traces of the specified link, or all links when you use the 'all' option in the syntax. When you clear one or more links, they no longer exist and cannot be reopened or used. If you are ending your programming session and do not want to retain any of the channels or links you created, use clear to end the RTDX communications and links and release all channels and resources associated with existing CCS IDE and RTDX links. You do not need to use the close or disable functions first.

• To load a new program to a processor on which you have a program running, and to which you have links, you must clear the existing links before you load the new program to the target.

• close--close the specified RTDX channel. To use the channel again, you must open and enable the channel. Compare close to disable. close('rtdx') closes the communications provided by RTDX. After you close RTDX, you cannot communicate with your target.
• disable--remove RTDX communications from the specified channel, but does not remove the channel, or link. Disabling channels may be useful when you do not want to see the data that is being fed to the channel, but you may want to read the channel later. By enabling the channel later, you have access to the data entering the channel buffer. Note that data that entered the channel while it was disabled is lost.
• halt--stop a running processor. You may still have one or more messages in the host buffer.

Use the following procedure to shut down communications between MATLAB and the target, and end your session:

1. Begin the process of shutting down the target and RTDX by stopping the target processor. Type the following functions at the prompt.

• if (isrunning)      % Use this test in scripts.
     cc.halt;         % Halt the processor.
  end                 % Done.
  

1. Your processor may already be stopped at this point. In a script, you might put the function in an if-statement as we have done here. Consider this test to be a safety check. No harm comes to the processor if it is already stopped when you tell it to stop. When you direct a stopped processor to halt, the function returns immediately.

2. You have stopped the processor. Now disable the RTDX channels you opened to communicate with the target.

• cc.rtdx.disable('all');
  

1. If necessary, using disable with channel name and target identifier input arguments lets you disable only the channel you choose. When you have more than one board or processor, you may find disabling selected channels meets your needs.

   When you finish your RTDX communications session, disable RTDX to ensure that the MATLAB Link for Code Composer Studio releases your open channels before you close them.

   • cc.rtdx.disable;
     

3. Use one or all of the following function syntaxes to close your open channels. Either close selected channels by using the channel name in the function, or use the 'all' option to close all open channels.
• cc.rtdx.close('ichan') to close your input channel in this tutorial.
• cc.rtdx.close('ochan') to close your output channel in the tutorial.
• cc.rtdx.close('all') to close all of your open RTDX channels, regardless of whether they are part of this tutorial.

1. Consider using the 'all' option with the close function when you finish your RTDX work. Closing channels reduces unforeseen problems caused by channel objects that may exist but do not get closed correctly when you end your session.

4. When you created your RTDX link (cc = ccsdsp('boardnum',1) at the beginning of this tutorial, the ccsdsp function opened CCS IDE and set the visibility to 0. To avoid problems that occur when you close the link to RTDX with CCS visibility set to 0, be sure to make CCS IDE visible on your desktop. The following if-statement checks the visibility and changes it if needed.

• if cc.isvisible,
      cc.visible(1);
  end
  

Note    Visibility can cause problems. When CCS IDE is running invisibly on your desktop, meaning you set visibility to 0, do not use clear all to get rid of your links for CCS IDE and RTDX. Without a link to CCS IDE you cannot access CCS IDE to change the visibility setting, or unload the application. To close CCS IDE when you do not have an existing link, either create a new link to CCS IDE, or use Windows Task Manager to end the process cc_app.exe, or close MATLAB.

5. You have finished the work in this tutorial, type the following to close all your remaining links to CCS IDE and release all the associated resources.

• clear ('all'); % Calls the link destructors to remove all links
  echo off
  

1. Note that clear all (without the parentheses) removes all variables from your MATLAB workspace.

You have completed the tutorial using RTDX. During the tutorial you:

1. Opened links to CCS IDE and RTDX and used those links to load an executable program to your target processor.
2. Configured a pair of channels so you could transfer data to and from your target.
3. Ran the executable on the target, sending data to the target for processing and retrieving the results.
4. Stopped the executing program and closed the links to CCS IDE and RTDX.

In future development work with your signal processing applications you follow the same set of tasks. Thus the tutorial provided here gives you a working process for using the MATLAB Link for Code Composer Studio and your signal processing programs to develop programs for a range of Texas Instruments digital signal processors. While the target may change, the essentials of the process remain the same.

Running the Application

Listing the Functions for Links