DSP System Toolbox

Fixed-Point Implementation and Code Generation for DSP System Models

You can use DSP System Toolbox with Fixed-Point Designer to model fixed-point signal processing algorithms and analyze the effects of quantization on system behavior and performance.

Fixed-point support in the system toolbox includes:

  • Word sizes from 1 to 128 bits
  • Overflow handing and rounding methods
  • Logging overflows, maxima, and minima of internal variables
  • Manual or automatic scaling
  • Data type override options to control system-level data type settings

Fixed-Point Modeling and Simulation

You can configure System objects and blocks in the system toolbox for fixed-Point modes of operation, enabling you to perform design tradeoff analyses by running simulations with different word lengths, scaling, overflow handling, and rounding method choices before you commit to hardware.

Fixed-point modes are supported for several DSP algorithms, including:

  • FFT, DCT, IFFT, IDCT, and other signal transforms
  • Digital Filter, Biquad Filter, LMS Filter, and other filter implementations
  • Mean, Variance, Autocorrelation, Histogram, and other statistics
  • Levinson-Durbin, Forward Substitution, Backward Substitution, and other linear system solvers
  • Matrix Multiply, Matrix Product, Matrix Sum, Matrix 1-Norm, and other matrix operations
  • Cumulative Product, Cumulative Sum, Difference, Normalization, and other math operations

In Simulink, DSP System Toolbox automates the configuration of blocks for fixed-point operation. For example:  

  • Accumulator and multiplier sizes are specified to ensure compatibility for specific hardware targets.
  • Binary point of a filter’s coefficient is automatically located based on user-defined word length, precision, and actual values.
  • Product output retains all bits in the products between filter coefficients and input values.
  • Accumulator is configured to avoid overflows.
Block dialog for FFT block in DSP System Toolbox.
Block dialog for FFT block in DSP System Toolbox. The dialog provides options for fixed-point data type specification of accumulator, product, and output signals (requires Simulink Fixed-Point).

Fixed-Point Filter Design

Filter design functions in DSP System Toolbox enable you to design floating-point filters that can be easily converted to fixed-point data types with Fixed-Point Toolbox. This design flow simplifies the design of fixed-point filters and lets you easily analyze quantization effects. 

Generating C and HDL Code

Using DSP System Toolbox with MATLAB Coder and Simulink Coder, you can generate C code from your algorithms and system models. The generated code can be used for verification, rapid prototyping, and implementation of your system during the product development process.

Using DSP System Toolbox with Filter Design HDL Coder, you can generate HDL code from digital filter designs. In Simulink, DSP System Toolbox blocks provide support for HDL code generation when used with HDL Coder.

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