Learn more about Signal Processing Blockset

N-Sample Enable - Output ones or zeros for specified number of sample times

Library

• Signal Processing Sources

  dspsrcs4

• Signal Management / Switches and Counters

  dspswit3

Description

The N-Sample Enable block outputs the inactive value (0 or 1, whichever is not selected in the Active level parameter) during the first N sample times, where N is the Trigger count value. Beginning with output sample N+1, the block outputs the active value (1 or 0, whichever you select in the Active level parameter) until a reset event occurs or the simulation terminates.

The output is always sample based.

The Reset input check box enables the Rst input port. At any time during the count, a trigger event at the input port resets the counter to its initial state. The reset sample time must be a positive integer multiple of the input sample time. This block supports triggered subsystems when you select the Reset input check box.

You specify the triggering event in the Trigger type pop-up menu:

• Rising edge — Triggers a reset operation when the Rst input does one of the following:

  • 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 reset operation when the Rst input does one of the following:

  • 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 reset operation when the Rst input is a Rising edge or Falling edge (as described above).

• Non-zero sample — Triggers a reset operation at each sample time that the Rst input is not zero.

  Note   When running simulations in the Simulink MultiTasking mode, sample-based reset signals have a one-sample latency, and frame-based reset signals have one frame of latency. Thus, there is a one-sample or one-frame delay between the time the block detects a reset event, and when it applies the reset. For more information on latency and the Simulink tasking modes, see Excess Algorithmic Delay (Tasking Latency) and Scheduling Considerations in the Real-Time Workshop User's Guide.

Dialog Box

Opening this dialog causes a running simulation to pause. See Changing Source Block Parameters During Simulation in the online Simulink documentation for details.

Trigger count

Specify the number of samples for which the block outputs the active value. Tunable.

Active level

Specify the value to output after the first N sample times, 0 or 1. Tunable.

Reset input

Select to enable the Rst input port. The rate of the reset signal must be a positive integer multiple of the rate of the data signal input.

Trigger type

Select type of event that triggers a reset when the Rst port is enabled.

Sample time

Specify the sample period, T_s, for the block's counter. The block switches from the active value to the inactive value at t=T_s*(N+1).

Output data type

Select the output data type.

Supported Data Types

• Double-precision floating point

• Boolean — The block accepts Boolean inputs to the Rst port, which is enabled when you set the Reset input parameter.

See Also

Counter	Signal Processing Blockset
N-Sample Switch	Signal Processing Blockset

Multiport Selector

N-Sample Switch

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