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System Modeling Blog

21 Jan, 2014

SystemVision Model Wizard

Posted by Mike Jensen

Mike Jensen I wrote a month or so ago about the challenge of finding — or creating — simulation models. In that post, I suggested there are three general categories of engineers looking for a model: Give me a model Help me understand the model Help me develop a model For the “help me develop a model” category, I mentioned Graphical Modeling and Language-based Modeling as two popular model … Read More

modeling tools, Modeling, SPICE

16 Dec, 2013

SystemVision 5.10.2

Posted by Mike Jensen

Mike Jensen SystemVision 5.10.2 is finished and available for immediate download from Mentor Graphics’ SupportNet website. What will you find in this new release? Here are some of the new/updated features and capabilities: Asymmetric parameter tolerances Custom, user defined statistical distributions Global Parameter support for Monte Carlo analysis details Worst Case and Extreme Value analysis support … Read More

10 Dec, 2013

Modeling: An Engineer's Dilemma

Posted by Mike Jensen

Mike Jensen Many of my recent interactions with customers have been on a single theme: modeling. Simulation is a great tool, but only if you have models that tell the simulator what to do. Models vary in type and complexity, but they all share a common purpose: to tell you something about how a device or system works, often in a specific application or under specific operating conditions. But there is a gap, an … Read More

SPICE, Modeling

16 Oct, 2013

What is Your Legacy?

Posted by Mike Jensen

Mike Jensen It happens every year in the fall: my birthday rolls around and I turn another year older. For good or bad, I am well into the time of my life where I have fewer years ahead of me than I do behind. I am not trying to be morose, just stating a fact. The numbers do not lie. And I suppose I am not unusual in occasionally looking back on my life wondering what my legacy will be. What will I be remembered … Read More

Career

30 Sep, 2013

Automotive IESF 2013

Posted by Mike Jensen

Mike Jensen Another IESF is in the Mentor Graphics history books. Record crowds gathered at the Ford Convention & Event Center in Dearborn, Michigan to learn about automotive system design using the latest Mentor Graphics tools. Along with hearing from keynote and industry speakers representing a broad spectrum of experience in automotive development, attendees chose from a long and varied list of technical … Read More

IESF, Mechatronic, SystemVision conneXion

3 Jul, 2013

Simple Design Solutions

Posted by Mike Jensen

Mike Jensen I recently spent some time at a big-box store, an international retailer specializing in home furnishings and décor. Not the type of store where I usually spend a lot of my shopping time, but friends and family rave about it, so I decided to make a quick visit to see what all the fuss is about. Aisles in this store are somewhat narrow and have a lot of twists and turns. They wander so much in and out … Read More

IEEE 1076.1, MAST, Mechatronics

5 Jun, 2013

SystemVision 5.10

Posted by Mike Jensen

Mike Jensen It is official: SystemVision 5.10 is finished and available for download from SupportNet. Even though this release took a bit longer than normal to complete, I believe the wait is worth it. Key among the new features are the following: Schematic symbol toolbar: Prior to SystemVision 5.10, placing symbols in a schematic required opening either SystemVision’s Search/Place Symbols dialog or DxDataBook … Read More

multi-physics

21 May, 2013

Engineering Muscle Memory

Posted by Mike Jensen

Mike Jensen I have written a time or two about my daughter’s piano recitals. As luck would have it, springtime is yet another popular recital season. This time my daughter had two – one for her own piano teacher’s studio, and the other as an invited duet accompanist to play in a friend’s recital. All-in-all, not a bad way to spend a mid-spring evening. As I listened to students play their prepared pieces, I noticed … Read More

Modeling, Mechatronics

6 May, 2013

EDA vs. Windows 8

Posted by Mike Jensen

Mike Jensen I have read a lot in recent months about Windows 8, Microsoft’s latest incarnation of its flagship Windows operating system. While there are many new features over and above its Windows 7 predecessor, one thing that makes me quite curious about Windows 8 is its optimization for touchscreen technology. Note that I have yet to use Windows 8, but I have used several other touchscreen devices on the market … Read More

25 Mar, 2013

VHDL-AMS Stress Modeling – Part 3

Posted by Mike Jensen

Mike Jensen I’ve been away from my blog for a couple of months helping the SystemVision Engineering team with a few details related to our upcoming release: SystemVision 5.10. We’re excited about this new release. It introduces, among other things, a new way to create simulation models from a variety of data sources. We think this new capability will make it much easier to create SystemVision simulation models. … Read More

Modeling

28 Jan, 2013

VHDL-AMS Stress Modeling - Part 2

Posted by Mike Jensen

Mike Jensen

In

Part 1

of this series I started work on a simple resistor model as a way to illustrate some of the flexibility the VHDL-AMS language offers when creating simulation models. Recall that one of the advantages of VHDL-AMS is adding detail to models – a benefit not available with all modeling languages or methods. With VHDL-AMS, it’s possible to get your model and simulator to report performance details not available with other tools. To illustrate this flexibility, my resistor model will include a power dissipation calculation, and a comparison of the result with a user defined power limit to determine stress conditions.

Before jumping into the next model piece, however, I’ll tie up a loose end I left dangling in my earlier post. I mentioned the use of “==” when formulating device equations in a VHDL-AMS model. And at that time I said to simply interpret the syntax as “equal to”. But that definition doesn’t quite cover what’s going on inside the simulator. The “==” is more accurately interpreted as “balance both sides of the equation”. Once the simulator generates a matrix of equations that represent the system, the unknowns are adjusted during simulation, through a series of iterations, until all equations are solved within a user defined accuracy.

Now back to my resistor model. I’m going to jump right into the next architecture, so if you need a review (or a preview) of the model so far, take a quick look at Part 1. Up to this point it’s a basic Ohm’s Law-based resistor: voltage across the resistor is directly proportional to the product of the current and resistance. Now it’s time to add commands to calculate the power.

Recall once again from your first physics or electric circuits class that the power dissipated in a resistor is dependent on any two of its three operating parameters: voltage, current, resistance. There are a few different combinations of these parameters that calculate power, but I’ll use the following:

power = voltage x current

Based on this equation, here is the next section in my model:

1: architecture power1 of resistor is

2: quantity vres across ires through p1 to p2;

3: quantity pwr : power;

4: begin

5: vres == ires*res;

6: pwr == v*i;

7: end architecture power1;

Here I’ve created a new architecture named “power1” for the resistor model. This architecture is the same as the “basic” architecture in my earlier post, except that its name is changed and Lines 3 and 6 are added to setup the power calculation. Line 3 defines a new quantity named “pwr” (remember that a quantity is an analog element in a model) with an assigned VHDL-AMS type of “power”. Note that pwr is not directly associated with the p1 and p2 ports of the model. Therefore the type assignment simply determines what units will be used (in this case “watts”) to plot the pwr quantity. Line 6 calculates pwr as the product of the voltage across the resistor and the current through it, as define in the standard power equation above. This architecture can be added to the model in Part 1 to create a resistor model with one entity and two architectures (recall that a VHDL-AMS model can only have one entity, but multiple architectures). When I use the resistor model in a SystemVision schematic, I can select which architecture to use for that resistor instance. If I choose the power1 architecture, the resistor’s power is calculated at each time or frequency step during the simulation, and becomes a waveform I can plot when the simulation is finished.

Now that my basic resistor is complete, I can add details that will determine if the power exceeds a user defined power rating. In Part 3 of this series I’ll create another new architecture that detects when the resistor’s power exceeds a user defined limit, and notifies me when there is a problem.

Read More

Modeling

7 Jan, 2013

VHDL-AMS Stress Modeling - Part 1

Posted by Mike Jensen

Mike Jensen One of the great values of modeling with a hardware description language is simply this: you can tell a model to calculate and report all sorts of information about what’s happening inside it. Consider a generic electrical model, for example. Simulators will report voltages across and currents through the device. But what if you want to know how much power is dissipated in the device? Or if the power … Read More

10 Dec, 2012

Practice! Practice!

Posted by Mike Jensen

Mike Jensen I recently attended a piano recital for a young man in my neighborhood who studies  music at a local university. He has natural musical aptitude and is an awesome piano talent. During his recital he played compositions from popular yet long since deceased composers: Beethoven, Liszt, Debussy, Prokofiev. If you’re not familiar with any of these names, not to worry. I only know them because my wife’s … Read More

Engineering Design

9 Nov, 2012

Sharing Tool Expertise

Posted by Mike Jensen

Mike Jensen In my last post I talked about using modeling and simulation to preserve design and technical expertise within a company. This seems a valuable methodology for preventing technical ‘brain drain’ within a corporation. Recently, however, I ran into another simulation dilemma related to sharing simulation knowledge: how to share simulation expertise between companies. Often when I talk with … Read More

Mixed-Signal

29 Oct, 2012

Preserving Expertise

Posted by Mike Jensen

Mike Jensen Like many youth since time began and there were pianos to play, my daughter takes piano lessons. In musical ways, she is much like her mom. Both play piano and sing beautifully. And like her mom, my daughter’s talent is several notches above average, at the level that leaves you wanting to hear more when each piece is over. I recently attended a recital to listen to my daughter and her fellow … Read More

Modeling

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