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Hold input data between samples

Specify how long subrate signal values are held in valid state

Model Configuration Pane: Test Bench

Description

Specify how long subrate signal values are held in valid state.

Dependencies

This option is disabled if you select the entire model. Select the DUT instead for Generate HDL for setting.

Settings

On (default) | Off
On

Data values for subrate signals are held in a valid state across N base-rate clock cycles, where N is the number of base-rate clock cycles that elapse per subrate sample period. (N >= 2.)

Off

Data values for subrate signals are held in a valid state for only one base-rate clock cycle. For the subsequent base-rate cycles, data is in an unknown state (expressed as 'X') until leading edge of the next subrate sample period.

Tips

In most cases, the default (On) is the best setting for Hold input data between samples. This setting matches the behavior of a Simulink® simulation, in which subrate signals are held valid through each base-rate clock period.

In some cases (for example modeling memory or memory interfaces), it is desirable to clear Hold input data between samples. In this way you can obtain diagnostic information about when data is in an invalid ('X') state.

To set this property, use hdlset_param or makehdltb. To view the property value, use hdlget_param.

For example, you can specify this parameter for the symmetric_fir subsystem inside the sfir_fixed model using either of these methods.

  • Pass the property as an argument to the makehdltb function.

    makehdltb('sfir_fixed/symmetric_fir', ... 
            'HoldInputDataBetweenSamples', 'off')

  • When you use hdlset_param, you can set the parameter on the model and then generate HDL code using makehdltb.

    hdlset_param('sfir_fixed', 'HoldInputDataBetweenSamples', 'off')
makehdltb('sfir_fixed/symmetric_fir')

Recommended Settings

No recommendations.

Programmatic Use

Parameter: HoldInputDataBetweenSamples
Type: character vector
Value: 'on' | 'off'
Default: 'on'

Version History

Introduced in R2012a