Byte Unpacking

Deconstruct data frames

• 

Libraries:
Simulink Real-Time / Utilities

Description

The Byte Unpacking block converts a vector of varying data types into one or more signals of user-selectable data types. The input of this block typically connects to an output port of a Receive block.

The Byte Packing block and the Byte Unpacking block support Simulink^® Real-Time™ STF code generation targets and generate code that runs on Speedgoat target machines. Due to considerations such as endianness and addressable word size, these blocks can generate incorrect results for other code generation targets or target computers.

For example, suppose that you are unpacking a uint8 vector signal into three signals. The signals have these attributes:

Dimension	Size	Type
Scalar	1	single
Vector	3	uint8
Vector	3	uint8

1. Set the output port data type to:

   {'single', ['uint8'], ['uint8']}

   Use square brackets to represent vectors.

2. Set the output port dimension to:

   {[1],[3],[3]}

3. Set the alignment value to 1.

4. Connect the output signals to the Byte Unpacking block.

Examples

Simple ASCII Encoding/Decoding Loopback Test (with Baseboard Blocks)

Convert a single floating point number to ASCII and transmit the value over a serial link.

• Open Script

ASCII Encoding/Decoding Loopback Test

Send ASCII data over a serial link.

• Open Script

ASCII Encoding/Decoding Loopback Test (with Baseboard Blocks)

Send ASCII data over a serial link.

• Open Model

ASCII Encoding/Decoding Resync Loopback Test

Use the ability of the FIFO Read HDRS block to resynchronize after being repeatedly disabled and apply this ability to resolve errors such as when a message is only partially complete at the time the read is attempted.

• Open Script

ASCII Encoding/Decoding Resync Loopback Test (with Baseboard Blocks)

Use the ability of the FIFO Read HDRS block to resynchronize after being repeatedly disabled and apply this ability to resolve errors such as when a message is only partially complete at the time the read is attempted.

• Open Script

Binary Encoding/Decoding Loopback Test

Send Binary data over a serial link.

• Open Script

Binary Encoding/Decoding Loopback Test (with Baseboard Blocks)

Send Binary data over a serial link.

• Open Script

Binary Encoding/Decoding Resync Loopback Test

Use the ability of the FIFO Read BINARY block to handle messages that are interrupted and only partially complete.

• Open Script

Binary Encoding/Decoding Resync Loopback Test (with Baseboard Blocks)

Use the ability of the FIFO Read BINARY block to handle messages that are interrupted and only partially complete.

• Open Script

Ports

Input

Port_1 — Input port containing packed data

vector

The block displays one input port that receives a vector of packed data. The source of the packed data determines by inheritance the data type of the packed data.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean

Output

Port_1 — First of N output ports

scalar | vector

The block displays from 1 to N output ports, as specified by elements of the cell array in the parameter Output port (unpacked) data types (cell array).

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean

Parameters

Output port (unpacked) data types (cell array) — Data types for the unpacked output signals

uint8 (default) | double | single | int8 | int16 | uint16 | int32 | uint32 | boolean

Specify as a cell array the data types of the output ports (unpacked) for the different output signals. The number of elements in the cell array determines the number of output ports shown by this block instance. To represent vector elements, use square brackets in the cell array.

Programmatic Use

Block Parameter: MaskUnpackedDataTypes

Output port (unpacked) dimensions (cell array) — Dimensions of each output port (unpacked)

{[1]} (default) | {[N], [M], ...}

Specify the dimensions of the output ports as a cell array of vectors.

Programmatic Use

Block Parameter: MaskUnpackedDataSizes

Byte Alignment — Alignment of the output signal data types before unpacking

1 (default) | 2 | 4 | 8

Each element in the output signals list starts at a multiple of the alignment value, specified from the start of the input vector. If the alignment value is larger than the size of the data type in bytes, the vector contains pad bytes of value 0.

For example, if the alignment value is 4:

• uint32 receives no padding

• uint16 receives 2 bytes of padding

• uint8 receives 3 bytes of padding

Programmatic Use

Block Parameter: MaskAlignment

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

The Byte Unpacking block supports C++ code generation only.

Version History

Introduced in R2006a