Start Code Composer Studio for DSK6713 and use Debug -> Connect

Figure 10: Startup Screen for Code Composer Studio (CCS)

Start MATLAB 7.3.0 R2006b:

Figure 11: Opening an Existing Demo

Click on “Demos”. The following screen will appear:

Figure 12: Selecting the Audio Demo Models

Highlight “Embedded Target for TI C6000 DSP” then “Audio”. Click on “Wavelet Denoising”. We are going to use this as our template.

The “Wavelet Denoising” model is now displayed.

Figure 13: Wavelet Denoising Parent

For convenience, save the model to the MATLAB “Work” directory, where most models are stored.

Figure 14: Saving the Model to the MATLAB “Work” directory

Delete the “Info” box. Change the title to “LMS Noise Reduction”. You may also wish to move the “DSK6713” icon to the left hand side.

Figure 15: LMS Noise Reduction Parent

Double-click on the “function()” box. The “Wavelet Noise Reduction Algorithm” model is now displayed.

Figure 16: Wavelet Denoising Algorithm

Delete the blocks and connect the input directly to the output. Add a title.

Figure 17: LMS Denoising Algorithm Template

We are going to implement the model shown below.

We will now update the empty model by dragging-and-dropping some library components onto the model.

Figure 18: Overview of the LMS Algorithm

Double-click on the blue box to the left marked “DSK6713 ADC”. The following screen will appear.

Figure 19: Setting up the ADC for Mono Microphone Input

Change the “ADC source” to “Mic In”.

If you have a quiet microphone, select “+20dB Mic gain boost”.

Set the “Sampling rate (Hz)” to “48 kHz”.

Set the “Samples per frame” to 64.

When done, click on “OK”.

Important: Make sure the “Stereo” box is empty.

The DAC settings need to match those of the ADC. Check that it uses the same sampling rates. Click on “OK”.

Figure 20: Setting the DAC Parameters

The Simulink block for LMS is to be found in the “Signal Processing Toolbox”.

Select View -> Library Browser -> Signal Processing Blockset ->Filtering-> Adaptive Filters.

Highlight “Adaptive Filters”. Drag-and-drop the “LMS Filter” block onto the model.

Figure 21: Adding an LMS Filter Block

The most critical variable in an LMS filter is the “Step size (mu)”.

If “mu” is too small, the filter has very fine resolution, but reacts too slowly to the audio signal.

If “mu” is too great, the filter reacts very quickly, but the error also remains large.

We will start with 0.005.

Figure 22: Setting the Parameter “Set size (mu)”

From the “Signal Processing Blockset”, highlight “Signal Operations”. Drag-and-drop the “Delay”1 block onto the model.

Figure 23: Adding a Delay

Because we are working with frames of 64 samples, it is convenient configure the delay using frames. Double-click on the “Delay” block.

Change the “Delay units” to Frames.

Set the “Delay (frames)” to 1. This makes the delay 64 samples.

Figure 24: Setting the Delay Size

So we can hear the difference without LMS denoising and with LMS noise reduction, we will use a DIP switch of the DSK6713.

Figure 25: Adding a Switch and LED

Select View -> Library Browser -> Embedded Target for TI C6000 DSP. Highlight “DSK6713 Board Support”.

Drag-and-drop the “Switch” block onto the model. Also drag-and-drop the “LED” block onto the model.

The DIP switch needs to be configured. Double-click on the “Switch” block.

Select all the boxes and set “Data type” to Integer. The “Sample time” should also be set to “–1”.

Figure 26: Setting up the DIP Switch Values

We now need to setup a way to switch between straight through without noise reduction and with LMS noise reduction.

Select View -> Library Browser -> Simulink. Highlight “Commonly Used Blocks”.

Drag-and-drop a “Constant” onto the model.

Drag-and-drop a “Switch” block onto the model.

Drag-and-drop a “Relational Operator” block onto the model.

Figure 27: Selecting the Commonly Used Blocks

The switch values lie between 0 and 15. We will use switch values 0 and 1. Double-click on the “Constant” block. Set the “Constant value” to 1 and the “Sample time” to “inf”.

Figure 28: Setting the Echo Delay Gain

Click on the “Signal Data Types” tab. Set the “Output data type mode” to “int16”. This is compatible with the DAC on the DSK6713.

Figure 29: Data Type Conversion to 16-bit Integer

Double click on the “Relational Operator” block. Change the “Relational operator” to “==”. Click on the “Signal Data Types” tab.

Figure 30: Changing the Relational Operator

Set the “Output data type mode” to “Boolean”. Click on “OK”.

Figure 31: Changing the Output Data Type

Move the blocks and join them as shown in the Figure below.

Figure 32: Joining the Blocks

From the Toolbar, select the “Up Arrow” icon. This returns you to the next higher level.

Figure 33: Returning to the Parent System

Select Tools -> Real-Time Workshop -> Build Model.

Figure 34: Building the Model

When built, the single lines are replaced by double lines. This shows frames.

Figure 35: Frames

From the folders on the left, select the source code for the project.

Figure 36: The Completed Model Running in Code Composer Studio

To check out the microphone and loudspeakers, set the DIP switches on the DSK6713 as follows:

Figure 37: Switch Position 0

The microphone is fed directly to the loudspeakers. There is no LMS noise reduction.

To run the “LMS Noise Reduction” subsystem, set the DIP switch to 1.

Figure 38: Switch Position 1 for LMS Noise Reduction