Delay size threshold for external memory (kilobytes)

Maximum delay size for external memory

Since R2023a

Model Configuration Pane: Optimization / Frame to Sample Conversion

Description

Use this parameter to specify a threshold size in kilobytes to map large integer delays to input and output DUT ports and offload large delays to external memory outside of your FPGA. Offloading delays to external memory is useful when a design requires an input frame be delayed and operated on and the delays do not fit on the chip block RAM. For example, if your design requires a comparison between two different frames, which creates a large delay, set this threshold parameter to save resources on your FPGA that would otherwise be used to store the delay.

Dependencies

To enable this parameter, select Enable frame to sample conversion.

Settings

10000 (default)

Enter a threshold value N that is greater than or equal to one to map delays greater than or equal to N to external memory by using input and output DUT ports. When you use the default value 10000, HDL Coder™ maps delays with a register size of 10000 kilobytes or greater to external memory.

Tips

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

For example, you can use DelaySizeThreshold to offload the memory required for a 4k frame, 8250 kilobytes of external memory storage, by setting the DelaySizeThreshold value to 8250.

You can then use DelaySizeThreshold when you generate HDL code for a DUT subsystem in a model using either of these methods:

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

    makehdl('<model_name/DUT_name>', ... 
        'DelaySizeThreshold',8250)

  • When you use hdlset_param, set the parameter on the model and then generate HDL code by using the makehdl function.

    hdlset_param('<model_name>','DelaySizeThreshold',8250)
makehdl('<model_name/DUT_name>')

Programmatic Use

Parameter: DelaySizeThreshold
Type: double
Value: double value greater than or equal to 1
Default: 10000

Version History

Introduced in R2023a

See Also

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