Compare To Zero

Determine how signal compares to zero

• Library:

• Simulink / Logic and Bit Operations

  HDL Coder / Logic and Bit Operations

• 

Description

The Compare To Zero block compares an input signal to zero. Specify how the input is compared to zero with the Operator parameter.

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

Ports

Input

Port_1 — Input signal

scalar

Input signal, specified as scalar, is compared with zero. If the input data type cannot represent zero, parameter overflow occurs. To detect this overflow, go to the Diagnostics > Data Validity pane of the Configuration Parameters dialog box and set Parameters > Detect overflow to warning or error.

In this case, the block compares the input signal to the ground value of the input data type. For example, if you have an input signal of type fixdt(0,8,2^0,10), the input data type can represent unsigned 8-bit integers from 10 to 265 due to a bias of 10. The ground value is 10, instead of 0.

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

Output

Port_1 — Output signal

0 | 1

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

The block output is uint8 or boolean, depending on your selection for the Output data type parameter.

Data Types: uint8 | Boolean

Parameters

Operator — Logical operator

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

This parameter can have the following values:

• == — Determine whether the input is equal to zero.

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

• < — Determine whether the input is less than zero.

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

• > — Determine whether the input is greater than zero.

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

Programmatic Use

Block Parameter: relop

Type: character vector

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

Default: '<='

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'

Model Examples

Variable-Size Signal Basic Operations

How variable-size signals can be generated. It also illustrates some of the operations that can be applied to them. The purpose of this example is to introduce the basic operations associated with variable-size signals.

Open Model

View Sequential Logic Through State Transition Matrix

Use the State Transition Matrix view for a state transition table in Stateflow®. Instead of drawing states and transitions graphically in a Stateflow chart, use state transition tables to express the modal logic in tabular format. State transition tables are supported only as blocks in a Simulink® model. For more information, see State Transition Tables in Stateflow (Stateflow).

Block Characteristics

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

Extended Capabilities

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

HDL Code Generation

Generate Verilog and VHDL 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