Fixed-Point Blockset Release Notes |

Fixed-Point Blockset 3.0 Release Notes

**New Features**

This section introduces the new features and enhancements added in the Fixed-Point Blockset 3.0 since the Fixed-Point Blockset 2.0 (Release 11.0).

This section is organized into these subsections:

- New Blocks
- New Functions
- Data Type Support
- Data Type and Scaling Inheritance
- Increased Speed, Efficiency, and Accuracy
- Overflow Logging
- Simulink Accelerator
- Model Parameter Configuration
- Display of Scaling Information

**New Blocks**

The Fixed-Point Blockset 3.0 includes the new blocks listed below.

Block Name |
Description |

Abs |
Output the absolute value of the input. |

Bitwise Operator |
Perform the specified bitwise operation on the inputs. |

Data Type Propagation |
Configure the data type and scaling of the propagated signal based on information from the reference signals. |

Dead Zone |
Provide a region of zero output. |

Dot Product |
Generate the dot product. |

Gateway In Inherited |
Convert a Simulink data type to a Fixed-Point Blockset data type, and inherit the data type and scaling. |

Integer Delay |
Delay a signal N sample periods. |

Look-Up Table Dynamic |
Approximate a one-dimensional function using a selected look-up method and a dynamically specified table. |

MinMax |
Output the minimum or maximum input value. |

Multiport Switch |
Switch output between different inputs based on the value of the first input. |

Sign |
Indicate the sign of the input. |

Tapped Delay |
Delay a scalar signal multiple sample periods, and output all the delayed versions. |

Unary Minus |
Negate the input. |

**New Functions**

The Fixed-Point Blockset 3.0 includes the new functions listed below.

Function Name |
Description |

fixptbestexp |
Determine the exponent that gives the best precision fixed-point representation of a value. |

fixptbestprec |
Determine the maximum precision available for the fixed-point representation of a value. |

fixpt_convert |
Convert Simulink models and subsystems to fixed-point equivalents. |

fixpt_convert_prep |
Prepare a Simulink model for more complete conversion to fixed point. |

fixpt_restore_links |
Restore links for fixed-point blocks. |

**Data Type Support**

The Fixed-Point Blockset 3.0 has expanded its data type support:

- You can connect Simulink blocks directly to Fixed-Point Blockset blocks provided the signals use built-in Simulink data types. However, a fixed-point signal consisting of 8-, 16-, or 32-bit integers is compatible with Simulink only when its scaling is given by a slope of
`1`

and a bias of`0`

. - Many important Simulink blocks have added support for fixed-point signals. Key blocks include Enable, Trigger, Scope, Display, and To Workspace.
- Fixed-point blocks now support complex numbers.

**Data Type and Scaling Inheritance**

Many fixed-point blocks support the inheritance of data type and scaling information from other blocks. The two possible inheritance options are:

- Inherit via internal rule--The output data type and scaling are inherited from the block input(s). The goal of the inheritance rule is to select the "natural" data type and scaling for the output. The specific rule that is used depends on the block operation. For example, if you are multiplying two signed 16-bit signals, the Product block produces the natural output of a signed 32-bit data type.
- Inherit via back propagation--The output data type and scaling are inherited by back propagation. In many cases, you will use the Data Type Propagation block with this option.

**Increased Speed, Efficiency, and Accuracy**

- Simulation speed has been increased by approximately 2.5 times.
- On average, fixed-point signals use 20 times less memory.
- Interpolation is more accurate and the number of quantization steps has been reduced.
- Generated code is significantly simpler.
- Unsigned numbers avoid overflow in these situations:

**Overflow Logging**

Indirect logging of overflows and saturations via percent range error has been replaced by explicit logging.

**Simulink Accelerator**

You can now use the Simulink Accelerator in conjunction with the Fixed-Point Blockset. However, you cannot log minimum and maximum simulation values or overflows.

**Model Parameter Configuration**

You can now use the **Model Parameter Configuration** dialog box to override the **Inline parameters** option for selected parameters. You access this feature by selecting the **Configure** button on the **Advanced** tab of the **Simulation Parameters** dialog box. Previously, code generation for fixed point blocks required all parameters to be inline, or all parameters to be tunable.

**Display of Scaling Information**

To significantly improve simulation speed, the scaling information associated with fixed-point blocks is no longer updated. Since this scaling information can become obsolete, you should remove it by running `fixpt_clear_tag`

or `slupdate`

. To view data type and scaling information, you should select **Port data types** under the model's **Format** menu.

Known Documentation Problem |