Embedded Target for Texas Instruments C6000 DSPs

Building Models

You can use C62x DSP Library blocks in models along with certain core Simulink, DSP Blockset, and Fixed-Point Blockset blocks. This section discusses issues you should consider when building a model with blocks from these different libraries.

Converting Data Types

As always, it is vital to make sure that any blocks you connect in a model have compatible input and output data types. In most cases, C62x DSP Library blocks handle only a limited number of specific data types. You can refer to any block reference page in Block Reference for a discussion of the data types that the block accepts and produces.

When you connect C62x DSP Library blocks and Fixed-Point Blockset blocks, you will often need to set the data type and scaling in the block parameters of the Fixed-Point Blockset block to match the data type of the C62x DSP Library block. Many Fixed-Point Blockset blocks allow you to set their data type and scaling through inheritance from the driving block, or through backpropagation from the next block. This can be a good way to set the data type of a Fixed-Point Blockset block to match a connected C62x DSP Library block.

Some DSP Blockset blocks and core Simulink blocks also accept fixed-point data types. Make the appropriate settings in these blocks' parameters when you connect them to a C62x DSP Library block.

However, to use DSP Blockset or core Simulink blocks that do not handle fixed-point data types in your model with C62x DSP Library blocks, you must use an appropriate data type conversion block:

• To connect fixed-point and nonfixed-point blocks, use the Gateway In and Gateway Out blocks in the Data Type library of the Fixed-Point Blockset.
• To serve as an interface to nonfixed-point blocks, use the Convert Floating-Point to Q.15 and Convert Q.15 to Floating-Point blocks in the C62x DSP Library.
• To connect blocks of varying nonfixed-point data types in your model, use the Data Type Conversion block in the Signals and Systems Simulink library
• To connect blocks of varying fixed-point data types in your model, use the Conversion and Conversion Inherited blocks in the Data Type library of the Fixed-Point Blockset.

See the reference pages of these blocks or invoke the Help from their dialogs for more information.

Using Sources and Sinks

The C62x DSP Library does not include source or sink blocks. Use source or sink blocks from the core Simulink library or DSP Blockset in your models with C62x DSP Library blocks. See Converting Data Types for more information on incorporating blocks from other libraries into your models.

Choosing Blocks to Optimize Code

In some cases, blocks that perform similar functions appear in more than one blockset. For example, both the C62x DSP Library and the DSP Blockset have an Autocorrelation block. How do you choose which to include in your model? If you are building a model to run on the C6711 DSK or C6701 EVM, choosing the block from the C62x DSP Library will always yield better optimized code. You can use a similar block from another library if it gives you functionality that the C62x DSP Library block does not support, but you will generate less well optimized code.

Q Format Notation

Using FDATool with the Embedded Target for TI C6000 DSP