Counter

Count up or down through specified range of numbers

expand all in page
  • Library:

  • DSP System Toolbox / Signal Management / Switches and Counters

  • Counter block

Description

The Counter block counts up or down through a specified range of numbers. The block enables the Inc (increment) port when you set the Count direction parameter to Up. When you set the Count direction parameter to Down, the block enables the Dec (decrement) port. If you set the Count event parameter to Free running, the block disables the Inc or Dec port and counts at a constant time interval. For all other settings of the Count event parameter, the block increments or decrements the counter each time a trigger event occurs at the Inc or Dec input port. When a trigger event occurs at the optional Rst port, the block resets the counter to its initial state.

The Counter block accepts single-channel inputs. For more information about scalar input operation, vector input operation, and free-running operation, see Algorithms.

Ports

Input

expand all

Input signal used to determine when the block increments or decrements the counter, specified as a real-valued scalar or vector. If the input to the Inc or Dec port is a vector, the block treats the vector as a frame. Each time a triggering event occurs at the Inc or Dec input port, the block increments or decrements the counter, respectively. You control the type of triggering event using the Count event parameter.

Dependencies

The block enables the Inc (increment) port when you set the Count direction parameter to Up.

The block enables the Dec (decrement) port when you set the Count direction parameter to Down.

The block disables the Inc/Dec input port when you set the Count event parameter to Free running. In free running mode, the block counts at a constant time interval.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Input signal used to determine when the block resets the counter, specified as a real-valued scalar. The Rst port must have the same port sample time as the Inc or Dec input port. Each time a triggering event occurs at the Rst port, the block resets the counter to its initial value. For more information about triggering events, see Count event.

Dependencies

To enable this port, select the Reset input check box.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Specify the maximum counter size as any unsigned integer that the Count data type can represent. The counter values range from 0 to the value you specify as an input to the Max port.

Dependencies

To enable this port, set the Counter size parameter to Specify via input port.

Data Types: uint8 | uint16 | uint32

Output

expand all

Current value of the counter, specified as a scalar or vector. When you set the Count event parameter to Free running, the Cnt output is a M-by-1 vector containing the count value at each of M consecutive sample times, where M is the value you specify for the Samples per output frame parameter.

Dependencies

To enable this port, set the Output parameter to Count or Count and Hit.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Hit status of the integer values you specified in the Hit values parameter. When a value you specify occurs in the count, the block outputs a 1 at the Hit port.

Note

The block might output Boolean values from the Hit output port depending on the setting of the Hit data type parameter.

Dependencies

To enable this port, set the Output parameter to Hit or Count and Hit.

Data Types: Boolean | Logical

Parameters

expand all

Specify whether to count Up or Down. The port label on the block icon changes to Inc (increment) or Dec (decrement) based on the value of this parameter.

  • When you set the Count direction parameter to Up and the counter reaches the upper limit of the counter range, the block restarts the counter at zero the next time a trigger event occurs at the Inc port.

  • When you set the Count direction parameter to Down and the counter reaches zero, the block restarts the counter at the upper limit of the counter range the next time a trigger event occurs at the Dec port.

This parameter is tunable (Simulink) in Simulink® normal mode.

Tunable: Yes

Specify the type of event that triggers the block to increment, decrement, or reset the counter when received at the Inc/Dec or Rst ports. You can select:

  • Rising edge — Triggers a count or reset operation when the input to the Inc/Dec or Rst port behaves in one of the following ways:

    • Rises from a negative value to a positive value or zero.

    • Rises from zero to a positive value, where the rise is not a continuation of a rise from a negative value to zero (see the following figure).

  • Falling edge — Triggers a count or reset operation when the input to the Inc/Dec or Rst port behaves in one of the following ways:

    • Falls from a positive value to a negative value or zero.

    • Falls from zero to a negative value, where the fall is not a continuation of a fall from a positive value to zero (see the following figure).

  • Either edge — Triggers a count or reset operation when the input to the Inc/Dec or Rst port is a Rising edge or Falling edge.

  • Non-zero sample — Triggers a count or reset operation at each sample time when the input to the Inc/Dec or Rst port is not zero.

  • Free running — Disables the Inc/Dec port and enables the Samples per output frame and Sample time block parameters. The block increments or decrements the counter at a constant interval, Ts, which you specify using the Sample time parameter. For more information, see Free-Running Operation. In this mode, the block resets the counter whenever it receives a non-zero sample at the Rst port.

Dependencies

When you set this parameter to Free running, the block disables the Inc/Dec port and counts at the constant interval specified by the Sample time parameter.

Specify the range of integer values the block counts through. When the block counts through the entire counter range, the next time a trigger event occurs at the Inc/Dec port, the block resets the counter as follows:

  • When you set the Count direction parameter to Up and the counter reaches the upper limit of the counter range, the block restarts the counter at zero.

  • When you set the Count direction parameter to Down and the counter reaches zero, the block restarts the counter at the upper limit of the counter range.

You can set the Counter size parameter to one of the following options:

  • 8 bits — Specifies a counter with a range of 0 to 255.

  • 16 bits — Specifies a counter with a range of 0 to 65535.

  • 32 bits — Specifies a counter with a range of 0 to 232–1.

  • User defined — Enables the Maximum count parameter, which allows you to specify the upper-count limit as any arbitrary unsigned integer that the Count data type can represent. The counter values range from 0 to the value of the Maximum count parameter.

  • Specify via input port — Enables the Max input port, which allows you to specify the upper-count limit as any arbitrary unsigned integer that the Count data type can represent. The counter values range from 0 to the value you specify as an input to the Max port.

Specify the maximum value of the counter as any unsigned integer representable by the data type you specify for the Counter data type parameter. Tunable (Simulink) in Simulink normal mode.

Tunable: Yes

Dependencies

To enable this parameter, set the Counter size to User defined.

Specify the initial value of the counter as any unsigned integer in the range defined by the Counter size parameter. The block uses the initial value of the counter at the start of simulation and resets the counter back to that initial value each time a trigger event occurs at the Rst port.

Tunable: Yes

Select the output ports to enable. You can choose to enable the Count, Hit, or Count and Hit ports.

Specify an integer or vector of integers whose occurrence in the count should be flagged by a 1 at the (optional) Hit output port. This parameter appears only when you set the Output parameter to Hit or Count and Hit.

Tunable: Yes

Select this check box to enable the Rst input port. When you enable the Rst port, the block resets the counter to its initial value each time a trigger event occurs at the Rst port. To specify the type of event that triggers a reset of the counter, set the Count event parameter. When you clear the Reset input check box, you cannot reset the counter during simulation.

Specify the number of samples, M, in each output vector as a positive integer.

Dependencies

To enable this parameter, set the Count event to Free running.

Specify the constant interval, Ts, at which the block increments or decrements the counter when in free-running mode. You can specify a scalar that is greater than or equal to zero, or specify a value of -1 to inherit the sample time.

For example, to have the block increment the counter every 5 seconds, set the Count direction parameter to Up, the Count event parameter to Free running, and specify a value of 5 for the Sample time parameter. In free running mode, the sample time of the output ports is always MTs.

Dependencies

To enable this parameter, set the Count event to Free running.

Specify the data type of the output at the Cnt port.

Dependencies

To enable this parameter, set the Output parameter to Count or Count and Hit.

Specify the data type of the output at the Hit port.

Dependencies

To enable this parameter, set the Output parameter to Hit or set it to Count and Hit with the Count data type parameter set to Double.

Model Examples

Count Down Through Range of Numbers

Count Down Through Range of Numbers

Use the Counter block to count down through a range of numbers. The Pulse Generator block drives the Dec port of the Counter block, and the N-Sample Enable block triggers the Rst port.

Block Characteristics

Data Types

Boolean | double | integer | single

Direct Feedthrough

no

Multidimensional Signals

no

Variable-Size Signals

no

Zero-Crossing Detection

no

Algorithms

expand all

Extended Capabilities

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

See Also

Blocks

Introduced before R2006a

DSP System Toolbox Documentation

Support