Counter Free-Running

Count up and overflow back to zero after reaching maximum value for specified number of bits

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Libraries:
Simulink / Sources
HDL Coder / Sources

Description

The Counter Free-Running block counts up until reaching the maximum value, 2^Nbits – 1, where Nbits is the number of bits. Then the counter overflows to zero and begins counting up again.

After overflow, the counter always initializes to zero. However, if you select the global doubles override, the Counter Free-Running block does not wrap back to zero.

Note

This block does not report wrap on overflow warnings during simulation. To report these warnings, see the Simulink.restoreDiagnostic reference page. The block does report errors due to wrap on overflow.

Examples

Bit Specification Using a Positive Integer

This example shows how to specify the Number of bits in the Counter Free-Running block as a positive integer.

At t = 255, the counter reaches the maximum value of (2^8)-1. If you increase the stop time of the simulation to 256, the counter wraps to zero.

Bit Specification Using an Unsigned Integer Expression

This example shows how to specify the Number of bits in the Counter Free-Running block as an unsigned integer expression.

At t = 254, the counter reaches the maximum value of uint8(2^(uint8(8))-1). If you increase the stop time of the simulation to 255, the counter wraps to zero.

Ports

Output

Port_1 — Count value

scalar

Count value, returned as an unsigned integer with a length specified by the Number of Bits parameter. When the number of bits is anything other than 8, 16, 32, or 64, the output type is an unsigned fixed-point data type.

Data Types: uint8 | uint16 | uint32 | uint64 | fixed point

Parameters

Number of Bits — Number of bits

16 (default) | scalar

Specify the number of bits as a finite, real-valued. When you specify:

• A positive integer, for example 8, the block counts up to 28 – 1, which is 255.

• An unsigned integer expression, for example uint8(8), the block counts up to uint8(2uint8(8) – 1), which is 254.

Programmatic Use

Block Parameter: NumBits

Type: character vector

Values: scalar

Default: '16'

Sample time — Interval between samples

-1 (default) | scalar | vector

Specify the time interval between samples as a scalar (sampling period), or a two-element vector ([sampling period, initial offset]). To inherit the sample time, set this parameter to -1. For more information, see Specify Sample Time.

Programmatic Use

Block Parameter: tsamp

Type: character vector

Values: scalar | vector

Default: '-1'

Block Characteristics

Data Types	fixed point | integer
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Extended Capabilities

C/C++ Code Generation

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

Not recommended for production code. Relates to resource limits and restrictions on speed and memory often found in embedded systems. Generated code can contain dynamic allocation and freeing of memory, recursion, additional memory overhead, and widely-varying execution times. While the code is functionally valid and generally acceptable in resource-rich environments, smaller embedded targets often cannot support such code. Usually, blocks evolve toward being suitable for production code. Thus, blocks suitable for production code remain suitable.

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).

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