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Bit Unpacking

Deconstruct data frames

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  • Bit Unpacking block

Libraries:
Simulink Real-Time / Utilities

Description

The Bit Unpacking block extracts data frames. Its input port is typically connected to an output port of a Receive block or Digital Input block.

The block has one input port, which represents the data frame entity from which the signals are extracted and leaving the block at its output ports. The number of output ports and the data type of each output port depend on the settings in the block dialog box.

Bit Unpack Four Bytes

This example shows how to configure a Bit Upacking block to:

  • Receive a 32-bit word as input by using input port data type uint32.

  • Unpack four 8-bit words (bytes) from the input data by using a bit pattern.

  • Send four 8-bit words as output by using the output data type uint8.

Configure the block by using the Bit Unpacking block parameters dialog box.

After configuring the block parameters, the Bit Upacking block appears as shown.

This Bit Unpacking block is configured to have four byte-wide outputs.

Examples

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

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.

ASCII Encoding/Decoding Loopback Test

ASCII Encoding/Decoding Loopback Test

Send ASCII data over a serial link.

ASCII Encoding/Decoding Loopback Test (with Baseboard Blocks)

ASCII Encoding/Decoding Loopback Test (with Baseboard Blocks)

Send ASCII data over a serial link.

ASCII Encoding/Decoding Resync Loopback Test

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.

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

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.

Binary Encoding/Decoding Loopback Test

Binary Encoding/Decoding Loopback Test

Send Binary data over a serial link.

Binary Encoding/Decoding Loopback Test (with Baseboard Blocks)

Binary Encoding/Decoding Loopback Test (with Baseboard Blocks)

Send Binary data over a serial link.

Binary Encoding/Decoding Resync Loopback Test

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.

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

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.

Parameters

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Specify bit patterns. The data type must be a MATLAB® cell array vector. The number of elements in the cell array define the number of input ports shown by this block instance. The cell array elements must be of type double array and define the position of each bit of the incoming value (data typed input port) in the outgoing double value (data frame). From a data type perspective, the block behaves like a Sink block. The Input port (packed) data types specify the data type of the input port.

Programmatic Use

Block Parameter: BitPatterns

From the list, select an input port (packed) data type.

Programmatic Use

Block Parameter: PackDataType

Specify the dimensions of the input port (packed). Enter this value as a vector. Specify the size of the port by using a format compatible with the MATLAB size command.

Programmatic Use

Block Parameter: PackDataSize

The output ports (packed) can be of an arbitrary data type. The number of elements in the cell array define the number of output ports shown by this block instance. The data types are:

  • double

  • single

  • int8

  • uint8

  • int16

  • uint16

  • int32

  • uint32

  • boolean

Programmatic Use

Block Parameter: UnpackDataTypes

Specify the dimensions of each output port (unpacked). Enter this value as a cell array of vector sizes.

Programmatic Use

Block Parameter: UnpackDataSizes

Select this check box to enable sign extension. If you select this check box and unpack the data frame into a signed type (int8, int16, or int32), the block performs sign extension. For example, if the bit pattern is [0:4], and the data type is int8, you are extracting 5 bits into an 8-bit wide signed type. In this case, bits 5, 6, and 7 are the same as bit 4, resulting in sign extension. This functionality enables you to pack and unpack negative numbers without losing precision.

Programmatic Use

Block Parameter: SignExtend

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2006a

See Also

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