Clock resolution (seconds, -1 for inherited)

Simulate target platform clock resolution

Since R2023a

Model Configuration Pane: Math and Data Types

Description

The Clock resolution parameter specifies the clock resolution that the code generator applies in generated code for functions in a model that include blocks that request absolute or elapsed time.

Clock resolution is the smallest increment of a clock value. For example, if a clock increments its value once per second, the clock resolution is 1 second. The parameter setting does not change solver behavior for normal, accelerator, and rapid accelerator mode simulations. However, the parameter setting does influence the data type that Simulink^® and the code generator use to represent time values. For example, Simulink uses a specified clock resolution to deduce fixed-point data types, which produces fixed-point simulation and generated code execution output that match.

How the code generator applies a specified clock resolution depends on the code interface configured for a model. For models that you configure with a data code interface, the clock resolution that you specify influences the clock tick in generated code. For models that you configure with a service code interface, the clock resolution influences timer service interface calls in the code. When you configure a model to use a service interface, you can specify a clock resolution that aligns with the clock resolution of a target platform. This results in entry-point function code that reads time values that are more accurate and can achieve improved real-time behavior.

Dependencies

To enable this parameter, set the solver parameter Type (SolverType) to Fixed-step.
This parameter requires an Embedded Coder® license for generating code.

Settings

-1 for inherited (default) | scalar

For models simulated in normal, accelerator, or rapid accelerator mode or configured with the System target file parameter set to ert.tlc, you can specify a scalar value, which represents the clock resolution in seconds.

Simulink and the code generator use the value to determine the word size of the data type for representing time values.
The code generator applies that value in generated code for model functions that include blocks that request absolute or elapsed time.

If a model includes a periodic function that includes a block that requests a time value, the value that you specify must divide the sample times used in periodic functions in the model with no remainder. For example, if a model includes periodic functions that use sample times 1, 0.2, and 0.1, then 0.05 is a valid clock resolution setting but value 0.03 is not valid. If the value that you specify for the clock resolution is not a divisor, you must change the clock resolution setting or the offending sample time.

For models configured with a system target file other than ert.tlc, or to get the clock resolution behavior that was provided in previous releases, set Clock resolution (seconds, -1 for inherited) to the default value (-1). When the parameter is set to -1, the code generator initializes clock resolutions based on scheduling properties for the model style and type of an entry-point function. For example, the code generator sets the clock resolution for an aperiodic function in an export-function model to the model fixed-step size (fundamental sample time). For periodic functions, the clock resolution is set to the function sample time.

Recommended Settings

Application	Setting
Debugging	No impact
Traceability	No impact
Efficiency	Positive integer
Safety precaution	`-1`

Programmatic Use

Parameter: ClockResolution

Type: double

Value: scalar

Default: -1

Version History

Introduced in R2023a