ECUs: More Than Just A Piece of Hardware

Raptor_ECU

Raptor_ECUChoosing an Electronic Control Unit (ECU) for your EV / HEV / Autonomous vehicle is a huge decision with implications way beyond vehicle control. While some people see it as ‘just a piece of hardware’, we believe your ECU choice greatly impacts your development process and ultimately what you’ll be able to deliver, and when. The supervisory or vehicle control unit you choose will affect your costs and even your to time to market in ways you may not anticipate.

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Understanding The Raptor Application Monitor Tool

raptor application monitor tool

The Application Monitor is a tool within Raptor-Dev that adds continuous run-time checking within your running application. It’s a useful tool for Embedded Model-Based Design (eMBD), especially if you begin to push the limits of the embedded hardware. Debugging software created in Simulink with Raptor is a little different than debugging a text-based programming language (like Python, C/C++, or MATLAB). For one, the generated code created from a Simulink model with Raptor generally won’t be familiar to the author of the model, which is kind of the point. It is the power of code generation that lets you go fast not having to worry about the detailed code. Secondly, the built software is programmed onto a sealed electronic control unit (ECU) with no hardware debugging attachments. Thankfully, with a robust, validated tool like Raptor-Dev and the proven code-generation technology from The Mathworks, the kinds of issues that require a hardware debugger are resolved already and available in the proven software blocks for your use.

Debugging an application without these debugging tools could be as simple as toggling an output on the ECU or changing the state of the system to something you would expect; however, some errors are more difficult to track down such as those in memory management which can cause intermittent microcontroller resets and other non-deterministic behavior. The App Monitor comes in handy when the system can’t be debugged by traditional debugging methods.

bricked_moduleNo controls system engineer wants to tote around a bricked module. Using the App Monitor offers a way to determine what might be resetting the processor by pausing the application during runtime. By stopping the application before a reset, the state of the module is available to be seen by the user. When the application is stopped, user-accessible variables are available for viewing.

 

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How Do I Use The Application Monitor?

By creating a model and simply dropping the “App Monitor” block onto the top-level system, we’ve done most of the heavy lifting.

monitor-application-toolThe parameters are as follows:

block-parameters-raptor-app-monitor

  • Enable App Monitor: The benefit of being able to control this is to easily remove debugging features in a production code build, after testing, such as with a script.
  • Startup Action:
    • App Monitor Disabled: Causes the App Monitor to be disabled (can also be set through calibration – see next parameter).
    • Run: Runs the software on startup
    • Pause: Pauses the software on startup
  • Add Startup Action Adjustment: This adds a calibration in Raptor-Cal under “Startup” that can be configured:
    • When set to pause, the application will pause on startup, as seen here. The foreground counter is at 0. The idle time is 0% because the application has never entered the foreground loop that updates this variable. Otherwise it would be at 100%.

AppMonitor-State-Startup-Application

  • Minimum Idle Time: The minimum percent of time that the processor can be idle before the App Monitor pauses the application.
  • Maximum Thread Time: The maximum percent of time that any particular thread may be active before the App Monitor pauses the application when checked against the Percent Overrun Limit.
  • Percent Overrun Limit: The percent of time a thread may be above the maximum thread time.

Within our model, we’re able to add more App Monitor logic that can give insight into CPU usage. The blocks shown below allow accessing App Monitor information at runtime. We’ll start by adding a few blocks. Stop the application by toggling “App Monitor Stop”. This kind of control is powerful if you can generate logic to stop the application when you prefer (for instance, by setting this stop point within a particular function call). This tag is viewable in Raptor-Cal.

adjustment-app-monitor-stopWhile stopping the application can help, the ability to see the underlying system parameters is more helpful. You can access this information by using the “App Monitor Measurement” block.

adjustment-app-monitor-stopVarious measurements include:

  • Idle Time: The measured percent of time that the processor is idle.
  • Trigger Usage: The percent of the scheduled time rate that the last execution of this rate task consumed. In this example, we have selected the “Foreground”. On all modules, the foreground trigger is fired every 5ms by default — except for the BCM48 and display, where the foreground rate default is 10ms.
  • Trigger Period: The measured amount of time since the last firing of a trigger.
  • Platform Items: On certain ECUs there are additional application monitoring data that is exposed by the base software. These platform-specific items are in this area.
  • Percent Overrun: The measured percent of time that a thread has overrun its time schedule.
  • Trigger Longest Run: The longest task execution time, measured in milliseconds.
  • Number of Overruns: A count of the number of times that a thread has exceeded the amount of time it’s allowed to run.

Adding these measurements to the model provides a simple application to show the inner-workings of the application, which is available for download.

For this demonstration, you can configure the App Monitor calibrations in Raptor-Cal to see how it works. In this screenshot, notice the main application counter is significantly lower than the AppMonitorExecutionCount (App Monitor execution counter) when the AppMonitorState is set to “Paused” (pausing the application).

app-monitor-execution-count

What To Take Away?

The Application Monitor allows for application debugging in settings where conventional debugging methods can’t help you. By stopping an app and/or seeing thread usage within the app, you can take better steps toward getting your application up and running.

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See New Eagle at the 2019 MathWorks MATLAB Expo

attend the 2019 matlab expo

Join New Eagle in San Jose, California at the MathWorks MATLAB Expo in the DoubleTree by Hilton San Jose on November 6, 2019. 

Meet with us at our booth where you will learn about Raptor, embedded Model-Based Development (eMBD) suite, our powerful platform for creating production control systems. See how Raptor’s tool suite leverages the open ECU development environment of MATLAB/Simulink to deliver the fast, flexible solutions developers need for rapid-prototyping. 

Plus, learn how the Raptor hardware line is delivering scalable solutions for today’s market-driven developers with its rugged, high-volume production offerings that support a complete production cycle.

Attending the MATLAB Expo is free, but registration is required. Sign up by clicking below, or learn more  on the MathWorks website.

 

raptor is a mathworks partner

See New Eagle at the 2019 Autonomous Vehicle Technology Expo

autonomous vehicle technology expo 2019

See Us at the AVT Expo in Booth AV231

Join New Eagle at the Suburban Collection Showplace in Novi, Michigan for the Autonomous Vehicle Technology Expo on October 22-24, 2019.

Connect with us  in booth AV231 to learn all about or innovative solutions for advancing autonomous vehicle technology, like our drive-by-wire kits. 

For more information or to register to attend, click below.

drive by wire vehicles
Take a Ride in our Drive-By-Wire Vehicles at Live Demo Day

Don’t miss your chance to take a spin in our drive-by-wire Pacifica and Jeep Cherokee at Live Demo Day on October 25, 2019.

This concluding event for the AVT expo gives you the opportunity to get up-close and personal with a range of innovation, all at Willow Run Airport  in Ypsilanti, Michigan. 

 

Beat the rush and schedule a demo ahead of time! Just email [email protected] to book your slot.