| Embedded Target for Texas Instruments C6000 DSPs | |
Task 2--Export Filter by Writing Directly to Target Memory
In Task 2 you export a filter by writing the filter coefficients directly to target memory. Before starting this task, you must allocate enough target memory for the filter coefficients by completing Task 1--Export Filter by Generating a C Header File. Once you have allocated enough target memory, you can tune your filter in FDATool and export the updated filter coefficients directly to the allocated target memory by following the steps in this task. For important guidelines on writing directly to target memory, see Cautions Regarding Writing Directly to Memory.
Step 9--Tune Your Filter in FDATool
Tune your filter coefficients in FDATool to improve its performance. Set the numerical precision of your filter by using the Quantized Filter pane in FDATool, available when you install the Filter Design Toolbox. If you do not have the Filter Design Toolbox, your filters in FDATool have the default precision, double-precision floating point.
If you have the Export to CCS IDE dialog open from Task 1, the dialog automatically updates itself as you tune the filter in FDATool. If you closed the dialog, reopen it as described in Step 2--Open the Export to Code Composer Studio (tm) IDE Dialog.
| Note If you allocated exactly enough memory for the filter coefficients in Task 1, you should not tune your filter such that it requires more memory than did the original filter (by increasing the filter order, for example). If you need more memory for your updated filter, allocate extra memory by editing the generated C header file from Task 1 (as described in the previous note), generating a program file, and loading the program file into your target. |
Step 10--Set the Export Mode
Set Export mode to Write directly to memory. Leave the parameter Disable memory transfer warnings unchecked so that you get a warning if your target does not support the export data type.
Step 11--Input Filter Variable Names
To write to the memory allocated in Task 1, enter the names of the variables in the target symbol table corresponding to the allocated memory. These names are the same as the names of the filter coefficient variables in the C header file from Task 1: NUM, DEN, NL, and DL. You do not need to type these names in, since they are the default setting of the Numerator, Denominator, Numerator length, and Denominator length parameters. (These parameters correspond to the memory locations that store the numerator filter coefficients, denominator filter coefficients, number of numerator coefficients, and number of denominator coefficients.)
Step 12--Set All Other Parameters for Export as in Task 1
Select an export data type and indicate your target DSP as in Steps 5 and 6 of Task 1.
Step 13--Load the Program File
Load the program file associated with your target into CCS IDE to activate the target symbol table. The program file must contain the global variables you entered in Step 11.
Step 14--Export by Writing Directly to Target Memory
Click Apply to export your filter. Before the filter export begins, a warning dialog appears if your target does not support the export data type. You can choose to continue to export the filter, or to cancel the export. To prevent this warning dialog from appearing, you can select the parameter Disable memory transfer warnings in Step 10.
Step 15 -- Continue Optimizing Filter Performance
Continue to optimize filter performance by retuning your filter in FDATool and exporting the updated filter coefficients directly to target memory. Since you already set up the export process to write to specific memory locations, you can click Apply to export updated coefficients to these same memory locations.
When the Export to CCS IDE dialog is open, it automatically updates as you tune your filter in FDATool, and preserves the parameter settings from Steps 10 through 13. The dialog stays open as long as you do not click Cancel or OK. Keep the dialog open when exporting multiple times to the same memory locations so you do not have to repeat Steps 10 through 13, and can just click Apply.
Where to Find More Information
For more information on exporting filters from FDATool to CCS IDE, see Guidelines on Exporting Filters from FDATool to CCS IDE, which contains the following sections:
To learn how to use FDATool, see the Filter Design and Analysis Tool section in the Signal Processing Toolbox documentation.
Also see the reference pages of the following Embedded Target for TI C6000 DSP functions:
| | Task 1--Export Filter by Generating a C Header File | Block Reference | |
