DSP Blockset Release Notes

Known Software Problems

The following sections describe some of the known DSP Blockset problems and limitations:

• Real-Time Workshop C Code Generation Limitations
• Nonzero Simulation Start Times Not Supported
• Triggered and Enabled Subsystem Support
• Digital Filter Design Block Limitations
• Magnitude FFT Block Limitations

Real-Time Workshop C Code Generation Limitations

C code generated from DSP Blockset blocks using Real-Time Workshop has the following limitations:

• DSP Blockset generally does not support the Loop rolling threshold parameter (visible when the Category parameter is set to General code generation options) in the Real-Time Workshop tab of the Simulink Simulation Parameters dialog.
• Currently, the DSP Blockset run-time library dsp_rt.lib does not always rebuild when you change compiler or linker options. Thus, before changing compiler and linker options, you should delete dsp_rt.lib and all associated object files. You can change compiler and linker options in the Simulink Simulation Parameters dialog's Real-Time Workshop tab by setting make command arguments such as OPTS or OPT_OPTS in the Make command parameter (for example, make_rtw OPTS="-DMYDEFINE=1").

Nonzero Simulation Start Times Not Supported

The DSP Blockset does not support nonzero simulation start times. When running a simulation with DSP Blockset blocks, you must set the Start time option in the Simulink Simulation Parameters dialog's Solver tab to 0.

Triggered and Enabled Subsystem Support

Triggered or enabled subsystems currently do not support the following blocks:

Buffer Counter Downsample Dyadic Analysis Filter Bank Dyadic Synthesis Filter Bank FIR Decimation FIR Interpolation Histogram Kalman Adaptive Filter LMS Adaptive Filter LU Solver Maximum Mean Minimum N-Sample Enable N-Sample Switch Overlap-Add FFT Filter Overlap-Save FFT Filter

Permute Matrix Queue Repeat RLS Adaptive Filter RMS Stack Standard Deviation Time-Varying Direct-Form II Transpose Filter Time-Varying Lattice Filter Unbuffer Upsample Variable Fractional Delay Variable Integer Delay Variable Selector Variance Wavelet Analysis Wavelet Synthesis

Digital Filter Design Block Limitations

The Digital Filter Design block has the following limitations:

• When you install the Filter Design Toolbox, FDATool, opened from the MATLAB command line, gets a new tab, Set Quantization Parameters. However, the Digital Filter Design block's FDATool does not currently support the Set Quantization Parameters tab.
• The Digital Filter Design block currently allows you to edit nontunable FDATool filter specification parameters. When you edit nontunable parameters during a simulation, the filter still updates in FDATool to reflect your changes. However, during simulation, FDATool only updates the block icon (which displays the frequency response of the updated filter). FDATool sends the new filter coefficients to the block only after the simulation stops running.

For details about the Digital Filter Design block, see the previous section, New Digital Filter Design Block.

Magnitude FFT Block Limitations

The Magnitude FFT block currently does not support 2-D sample-based 1-by-N row vector inputs.

Upgrading from an Earlier Release

DSP Blockset 4.0 Release Notes