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Tune and Monitor Executable Running on ARM Cortex-M QEMU

Using External Mode

You can use External mode to tune parameter values in, and receive data from, the executable while it runs on your target hardware.

External mode enables you to tune model parameters and evaluate the effects of different parameter values on the executable while it is running on the hardware. Doing so helps you find the optimal values. This process is called parameter tuning.

External mode accelerates parameter tuning. You do not have to generate code, build, and run the executable each time you change the value of a parameter. You can also use External mode to develop and validate your application using the actual data and hardware for which it is designed. This software-hardware interaction cannot be achieved solely by simulating a model.

This workflow lists the tasks usually required to tune parameters with External mode:

  1. (Optional) Place one or more sink blocks in your model. For example, use Display or Scope blocks to visualize data or a To File block to log signal data.

  2. Configure the model to simulate in External mode.

  3. Build and run the executable on the target hardware.

  4. Connect the model on your host computer to the executable running on the ARM® Cortex®-M QEMU.

  5. (Optional) On your host computer, observe the data that External mode sends from the executable running on the target hardware to the sink blocks in the model.

  6. On your host computer, change parameter values in the model that External mode applies to the executable running on the target hardware.

  7. Find the optimal parameter values by making adjustments and observing the results.

  8. Save the new parameter values, disable External mode in the model, and save the model.

Configure Simulink Model for External Mode

  1. Verify that you are able to run an executable on the ARM Cortex-M QEMU, as described in Build and Run Executable on ARM Cortex-Mx processor.

  2. In the model, review the default 10-second value of Simulation stop time parameter, located on the model toolbar.

    • To simulate in External mode for an indefinite period, enter inf. This setting is the best one for experimenting with different values on a variety of parameters.

    • To simulate in External mode for a finite period, enter a number of seconds. For example, if you enter 120, the executable runs on the target hardware for 2 minutes. This setting is the best one for limited testing of specific parameter values. When the model on the host computer stops simulating in External mode, it stops the executable running on the QEMU emulator.

  3. Click the Model Configuration Parameters button.

  4. In Configuration Parameters, select the Hardware Implementation pane.

  5. In the Hardware board, select ARM Cortex-M3 (QEMU) or , M4 or M55 or M7 processors option.

  6. Select External mode under Target Hardware Resources and set the required values in parameters.

Run an Executable on the ARM Cortex-M QEMU

  1. Verify that you are able to run an executable on the QEMU, as described in Build and Run Executable on ARM Cortex-Mx processor.

  2. In the model, set Simulation mode to External.

  3. Set the Simulation stop time parameter, located to the left of Simulation mode on the model toolbar. The default value is 10.0 seconds. To run the model for an indefinite period, enter inf.

    Note

    When model stops simulating in External mode, the binary executable stops running on the hardware.

  4. Optional: To observe data that External mode sends from the executable to the model on the host computer, place one or more sink blocks in your model. To visualize data, attach Display or Scope blocks to signals in the model. To log signal data, use a To File block. Also review the options under the Simulation Data Inspector button.

  5. Click the Run button.

    External mode:

    • Runs the binary executable on the QEMU.

    • Runs the model on the host computer in External mode.

    • Establishes External mode communication between the executable and the model.

    Note

    If your model does not contain a sink block, the MATLAB® Command Window displays a warning message. For example:

    Warning: No data has been selected for uploading. 
> In C:\Program Files (x86)\MATLAB\R2013a Student1\toolbox\
realtime\realtime\+realtime\extModeAutoConnect.p>
extModeAutoConnect at 17
In C:\Program Files (x86)\MATLAB\R2013a Student1\toolbox\
realtime\realtime\sl_customization.p>myRunCallback at 149

    You can disregard this warning or add a sink block to the model.

  6. Change block parameter values in the model on your host computer. External mode applies the new parameters values to the executable running on the QEMU. Observe the effects of those changes and optimize the parameter values.

    Any Simulink® Sinks blocks in your model receive data from the QEMU and display it on your host computer.

Stop External Mode

To stop the model simulating in External mode:

  1. Select Simulation > Stop, or click the stop button on the model toolbar.

    Note

    If the Simulation stop time parameter is set to a finite period, External mode stops when the period elapses.

  2. Stop the QEMU emulator by entering the following MATLAB command:

    codertarget.arm_cortex_m.stopQemu(pid)

    Replace pid with the PID the MATLAB Command Window displayed when you started the QEMU emulator.

    For example, in the MATLAB Command Window, enter:

    codertarget.arm_cortex_m.stopQemu(8500)

    The software displays the status of the emulator session. For example:

    Terminated QEMU process with PID 8500.
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