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

Library

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.

Data Type Support

The Counter Free-Running block outputs an unsigned integer.

For more information, see Data Types Supported by Simulink in the Simulink documentation.

Parameters and Dialog Box

Number of Bits

Specify the number of bits.

When you use...	Such as...	The block counts up to...	Which is...
A positive integer	8	28 – 1	255
An unsigned integer expression	uint8(8)	uint8(2uint8(8) – 1)	254

Sample time

Specify the time interval between samples. To inherit the sample time, set this parameter to -1. See How to Specify the Sample Time in the Simulink documentation.

Examples

Bit Specification Using a Positive Integer

Suppose that you have the following model:

The block parameters are:

Parameter	Setting
Number of Bits	8
Sample time	-1

The solver options for the model are:

Parameter	Setting
Stop time	255
Type	Fixed-step
Solver	discrete (no continuous states)
Fixed-step size	1

At t = 255, the counter reaches the maximum value:

2⁸ – 1

If you change the stop time of the simulation to 256, the counter wraps to zero.

Bit Specification Using an Unsigned Integer Expression

Suppose that you have the following model:

The block parameters are:

Parameter	Setting
Number of Bits	uint8(8)
Sample time	-1

The solver options for the model are:

Parameter	Setting
Stop time	254
Type	Fixed-step
Solver	discrete (no continuous states)
Fixed-step size	1

At t = 254, the counter reaches the maximum value:

uint8(2^uint8(8) – 1)

If you change the stop time of the simulation to 255, the counter wraps to zero.

Characteristics

Sample Time	Specified in the Sample time parameter
Scalar Expansion	No
Zero-Crossing Detection	No

See Also

Counter Limited

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