Embedded Target for Texas Instruments C6000 DSPs

C6701 EVM Tutorial 2-1--Single Rate Application

In this tutorial you create and build a model that simulates audio reverberation applied to an input signal. Reverberation is similar to the echo effect you can hear when you shout across an open valley or canyon, or in a large empty room.

You can choose to create the Simulink model for this exercise from blocks in DSP Blockset and Simulink block libraries, or you can find the model in the Embedded Target for TI C6000 DSP demos. For this example, we show the model as it appears in the demonstration program. The demonstration model name is c6701evmafxr.mdl as shown in the next figure. Open this model by typing c6701evmafxr at the MATLAB prompt.

To exercise this model you need a microphone connected to the Mic In connector on your C6701 EVM and speakers and an oscilloscope connected to the Line Out connector on your C6701 EVM. To test the model, speak into the microphone and listen to the output from the speakers. You can observe the output on the oscilloscope as well.

To download and run your model on your C6701 EVM, you complete the following tasks:

1. Use Simulink blocks and blocks from other blocksets to create your model application.
2. Add the Embedded Target for TI C6000 DSP blocks that let your signal sources and output devices communicate with your C6701 EVM--the C6701 EVM ADC and C6701 EVM DAC blocks that you find in the Embedded Target for TI C6000 DSP c6000lib blockset.
3. Configure the simulation parameters for your model, including:
• Simulation parameters such as simulation start and stop time and solver options
• Real-Time Workshop options such as target configuration and target compiler selection
4. Build your model to the selected target.
5. Test your model running on the target by changing the input to the target and observing the output from the target.

Your target for this tutorial is your C6701 EVM installed on your PC. Be sure to configure and test your board as directed in Configuring Your C6701 EVM in this guide before continuing this tutorial.

Building the Audio Reverberation Model

To build the model for audio reverberation, follow these steps.

1. Open Simulink:
2. Create a new model by selecting File -> New -> Model from the Simulink menu bar.
3. Use Simulink blocks to create the following model.

   

1. Look for the Integer Delay block in the Signal Operations library of the DSP Blockset. You do not need to add the input and output signal lines at this time. When you add the C6701 EVM blocks in the next section, you add the input and output to the sum blocks.

4. Save your model with a suitable name before continuing.

Adding C6701 EVM Blocks to Your Model

So that you can send signals to your C6701 EVM and get signals back from the board, the Embedded Target for TI C6000 DSP includes a block library containing five blocks designed to work with the codec on your C6701 EVM:

• Input block (C6701 EVM ADC)
• Output block (C6701 EVM DAC)
• Light emitting diode block (C6701 EVM LED)
• Software reset block (Reset C6701 EVM)
• DIP Switch block (C6701 EVM DIP Switch)

Typing C6701 EVMlib at the MATLAB prompt brings up this window showing the library blocks.

Figure 2-4: Embedded Target for TI C6000 DSP Target for C6701 EVM Block Library C6701 EVMlib

These blocks are included in the Embedded Target for TI C6000 DSP c6000lib blockset in the Simulink Library browser.

The C6701 EVM ADC and C6701 EVM DAC blocks let you configure the codec on your C6701 EVM to accept input signals from the input connectors on the board, and send the model output to the output connector on the board. Essentially, the C6701 EVM ADC and C6701 EVM DAC blocks add driver software that controls the behavior of the codec for your model.

To add C6701 EVM target blocks to your model, follow these steps:

1. Double-click Embedded Target for TI C6000 DSP in the Simulink Library browser to open the c6000lib blockset.
2. Click the library EVM Blocks to see the available blocks for your C6701 EVM.
3. Drag and drop C6701 EVM ADC and C6701 EVM DAC blocks to your model as shown in the figure.

   

4. Connect new signal lines as shown in the figure.

Configuring the Embedded Target for TI C6000 DSP Blocks

To configure the Embedded Target for TI C6000 DSP blocks in your model, follow these steps:

1. Click the C6701 EVM ADC block to select it.
2. Select Block Parameters from the Simulink Edit menu.
3. Set the following parameters for the block:
• Clear the Stereo check box
• Select the +20 dB mic gain boost check box
• From the list, set Sample rate to 8000
• Set Codec data format to 16-bit linear
• For Output data type, select Double from the list
• Set Scaling to Normalize
• Set Source gain to 0.0
• Enter 64 for Samples per frame

1. Include a signal path directly from the input to the output so you can display both the input signal and the modified output signal on the oscilloscope for comparison.

4. For C6701 EVM ADC source, select Mic In.
5. Click OK to close the C6701 EVM ADC dialog.
6. Now set the options for the C6701 EVM DAC block.
• Set Codec data format to 16-bit linear
• Set Scaling to Normalize
• For DAC attenuation, enter 0.0
• Set Overflow mode to Saturate.
7. Click OK to close the dialog.

You have completed the model. Now you configure the Real-Time Workshop options to build and download your new model to your C6701 EVM.

Creating Your Simulink Model for Targeting

Configuring Simulation Parameters for Your Model