Version 6.2 (R2009b) Simulink Fixed Point Software :: Simulink Fixed Point Release Notes (Simulink® Fixed Point™)

Version 6.2 (R2009b) Simulink Fixed Point Software

This table summarizes what's new in Version 6.2 (R2009b):

New Features and Changes	Version Compatibility Considerations	Fixed Bugs and Known Problems	Related Documentation at Web Site
Yes Details below	No	Bug Reports Includes fixes	Printable Release Notes: PDF Current product documentation

New features and changes introduced in this version are

Discrete Transfer Function Block Supports Fixed-Point Intrinsically

The Discrete Transfer Fcn block now accepts and outputs fixed-point signals.

New PID Controller Blocks Support Fixed-Point Intrinsically

In discrete-time, the new PID Controller and PID Controller (2 DOF) blocks accept real signals of any numeric data type supported by Simulink software, including fixed-point data types.

Rapid Accelerator Mode Now Supports All Fixed-Point Word Lengths for Parameters

Rapid Accelerator mode now supports fixed-point parameters up to 128 bits. To learn more about fixed-point considerations when accelerating your Simulink models, see Accelerator and Rapid Accelerator Mode Data Type Considerations in the Simulink User's Guide.

Lookup Table (n-D) Block Supports Parameter Data Types Different from Signal Data Types

The Lookup Table (n-D) block supports breakpoint data types that differ from input data types. This enhancement provides these benefits:

Lower memory requirement for storing breakpoint data that uses a smaller type than the input signal
Sharing of prescaled breakpoint data between two Lookup Table (n-D) blocks with different input data types
Sharing of custom storage breakpoint data in Real-Time Workshop^® generated code for blocks with different input data types

The Lookup Table (n-D) block supports table data types that differ from output data types. This enhancement provides these benefits:

Lower memory requirement for storing table data that uses a smaller type than the output signal
Sharing of prescaled table data between two Lookup Table (n-D) blocks with different output data types
Sharing of custom storage table data in Real-Time Workshop generated code for blocks with different output data types

The Lookup Table (n-D) block also supports separate data type specification for intermediate results. This enhancement enables use of a higher precision for internal computations than for table data or output data.

Reduced Memory Use and More Efficient Code for Evenly-Spaced Breakpoints in Prelookup and Lookup Table (n-D) Blocks

For the Prelookup and Lookup Table (n-D) blocks, Real-Time Workshop generated code now stores only the first breakpoint, spacing, and number of breakpoints when:

The breakpoint data is not tunable.
The index search method is Evenly spaced points.

This enhancement reduces memory use and provides faster code execution. Previously, the code stored all breakpoint values in a set, regardless of the tunability or spacing of the breakpoints.

The following enhancements also provide more efficient code for the two blocks:

Block	Enhancement for Code Efficiency
Lookup Table (n-D)	Removal of unnecessary bit shifts for calculating the fraction
Prelookup and Lookup Table (n-D)	Use of simple division instead of computationally-expensive function calls for calculating the index and fraction

Math Function Block Enhancements for Real-Time Workshop Code Generation

The Math Function block now supports Real-Time Workshop code generation for fixed-point data types with fractional slope and nonzero bias for the magnitude^2, square, and reciprocal functions.

Improved Fixed-Point Advisor Workflow

In R2009b, the new Fixed-Point Advisor workflow helps you convert your floating-point Simulink model to a fixed-point model more quickly and efficiently. You can now complete your first iteration through the conversion process without accepting all the recommendations. The new workflow ensures that you convert the entire model before preparing the model for code generation. For more information, see Tutorial: Converting a Model from Floating- to Fixed-Point and Fixed-Point Advisor Reference in the Simulink Fixed Point User's Guide.

New Optimization Option to Allow Integer Division to Handle Net Slopes that are Reciprocals of Integers

R2009b introduces a new optimization parameter, Use integer division to handle net slopes that are reciprocals of integers. When a change of fixed-point slope is not a power of two, net slope correction is necessary. Normally, net slope correction uses an integer multiplication followed by shifts. Enabling this new optimization replaces the multiplication and shifts with an integer division under certain simplicity and accuracy conditions. For more information, see Use integer division to handle net slopes that are reciprocals of integers in the Simulink Graphical User Interface.

Enhanced Model Advisor Check Identifies Opportunities to Improve Code Efficiency

The Model Advisor Identify questionable fixed-point operations check can:

Provide advice on when to use the new Use integer division to handle net slopes that are reciprocals of integers optimization parameter
For more information, see Use integer division to handle net slopes that are reciprocals of integers in the Simulink Graphical User Interface.
Identify opportunities to improve efficiency of generated code for Lookup Table (n-D) blocks in the following cases:
Breakpoint Spacing Index Search Method

Uneven Not Evenly spaced points

Even, power of 2 Not Evenly spaced points

Even, not power of 2 Not Evenly spaced points

Evenly spaced points

For more information, see Identify questionable fixed-point operations in the Real-Time Workshop Reference.

Breakpoint Spacing	Index Search Method
Uneven	Not `Evenly spaced points`
Even, power of 2	Not `Evenly spaced points`
Even, not power of 2	Not `Evenly spaced points`
`Evenly spaced points`

New Diagnostic Controls to Detect Precision Loss in Fixed-Point Constants

You can now enable the detection of precision loss in net slope and net bias correction. If you enable these diagnostics, the software alerts you when precision loss occurs. It also provides information about the original fixed-point constant value and the error introduced due to quantization or saturation. For more information, see Detect underflow, Detect overflow, and Detect precision loss in the Simulink Graphical User Interface.

Synchronized Zooming for Fixed-Point Tool Time Series Difference Plot

The Fixed-Point Tool now provides synchronized zooming for the Time Series Difference (A-R) plot. By default, zooming on either the Active and Reference plot or the Difference plot now zooms both plots. For more information, see Plot Interface in the Simulink Reference.

Changes in Text and Visibility of Dialog Box Prompts for Easier Use with Fixed-Point Advisor and Fixed-Point Tool

The Lock output scaling against changes by the autoscaling tool check box is now Lock output data type setting against changes by the fixed-point tools. Previously, this check box was visible only if you entered an expression or a fixed-point data type for the output, such as fixdt(1,16,0). This check box is now visible for any output data type specification. This enhancement enables you to lock the current data type settings on the dialog box against changes that the Fixed-Point Advisor or Fixed-Point Tool chooses.

Which blocks are enhanced?

The Lock scaling against changes by the autoscaling tool check box is now Lock data type settings against changes by the fixed-point tools. Previously, this check box was visible only if you entered an expression or a fixed-point data type, such as fixdt(1,16,0). This check box is now visible for any data type specification. This enhancement enables you to lock the current data type settings on the dialog box against changes that the Fixed-Point Advisor or Fixed-Point Tool chooses.

Which blocks are enhanced?

New and Enhanced Demos

The following demos have been added:

Demo...	Shows How You Can...
`Fault-tolerant Fuel Control System`	Perform a floating-point and a fixed-point simulation of a fuel rate control system designed using Simulink and Stateflow^®.