Compare To Constant

Determine how signal compares to specified constant

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Libraries:
Simulink / Logic and Bit Operations
HDL Coder / Logic and Bit Operations

Description

The Compare To Constant block compares an input signal to a constant. Specify the constant in the Constant value parameter. Specify how the input is compared to the constant value with the Operator parameter.

Examples

Illustration of Law of Large Numbers

Use MATLAB System blocks to illustrate the law of large numbers.

• Open Model

Ports

Input

Port_1 — Input signal

scalar | vector | matrix

Input signal, specified as a scalar, vector, or matrix, is compared with constant. The block first converts its Constant value parameter to the input data type, and then performs the specified operation.

Data Types: half | single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus

Output

Port_1 — Output signal

0 | 1 | vector | matrix

The output is 0 if the comparison is false, and 1 if it is true.

Data Types: uint8 | Boolean

Parameters

Operator — Logical operator

<= (default) | == | ~= | < | >= | >

This parameter can have these values:

• == — Determine whether the input is equal to the specified constant.

• ~= — Determine whether the input is not equal to the specified constant.

• < — Determine whether the input is less than the specified constant.

• <= — Determine whether the input is less than or equal to the specified constant.

• > — Determine whether the input is greater than the specified constant.

• >= — Determine whether the input is greater than or equal to the specified constant.

Programmatic Use

Block Parameter: relop

Type: character vector

Values: '==' | '~='| '<' |'<='| '>='| '>'

Default: '<='

Constant value — Constant to compare with

constant

Specify the constant value to which the input is compared.

Programmatic Use

Block Parameter: const

Type: character vector

Value: scalar | vector | matrix | N-D array

Default: '3.0'

Output data type — Data type of the output

boolean (default) | uint8

Specify the data type of the output, boolean or uint8.

Programmatic Use

Block Parameter: OutDataTypeStr

Type: character vector

Values:'boolean' | 'uint8'

Default: 'boolean'

Enable zero-crossing detection — Select to enable zero-crossing detection

'on' (default) | 'off'

Select to enable zero-crossing detection. For more information, see Zero-Crossing Detection.

Programmatic Use

Block Parameter: ZeroCross

Type: character vector

Values: 'off' | 'on'

Default: 'on'

Block Characteristics

Data Types	Boolean | double | enumerated | fixed point | half | integer | single
Direct Feedthrough	yes
Multidimensional Signals	yes
Variable-Size Signals	yes
Zero-Crossing Detection	yes

More About

Model Coverage

If you have a Simulink^® Coverage™ license, the Compare To Constant block receives condition coverage.

Condition coverage measures:

• The number of times that the comparison between the input and the specified constant is true

• The number of times that the comparison between the input and the specified constant is false

If you select the Relational boundary (Simulink Coverage) coverage metric, the Compare To Constant block receives relational boundary coverage. For more information, see Relational Boundary Coverage (Simulink Coverage).

Extended Capabilities

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

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).

Complex Data Support

This block supports code generation for complex signals.

PLC Code Generation
Generate Structured Text code using Simulink® PLC Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced before R2006a