editor's blog
Subscribe Now

Requirements Modeling and Simulation

Flow_image.jpgSo you’re working on a design… Are you sure you’re building what was intended? Yes, you’re building what they asked for… or, at least, what you think they asked for, but is that what they wanted?

Requirements can be dicey; they’re based on natural language, which, as we know all too well, is subject to interpretation. According to Argosim, many companies have institutionalized styles – sentence templates, for instance – to ensure consistent, clear, unambiguous articulation of requirements. That’s not a guarantee of clarity, but it certainly helps.

What it doesn’t necessarily help with, however, is the following question: do you know if, out of all the requirements, some of them conflict or are mutually inconsistent? If one requirement is a dense material to protect against radiation and another requirement is that the material has to float, those two might not work together.

There has, until recently, been no way to formally check requirements for consistency and overall requirements correctness. Those two requirements above (dense + floating) are relatively vague – you wouldn’t be able to test them without the ability to extract the semantics and then simulate the physics. But many requirements are functional, and they can be expressed in a more formal manner that can then be tested.

This might sound like a nice-to-have for many electronic products. We see too many cheap consumer goods that clearly haven’t been well thought out or possibly don’t even have all of their features working properly. This would be great for that, but such products typically have cost and schedule requirements that don’t really allow for a more thoughtful process.

Safety-critical equipment, however, is a completely different matter, having strict requirements for requirements traceability. And, while some product requirements will always have a level of vagueness, functional requirements in such systems explicitly must be verifiable. This means that they should be specific enough to have their mutual consistency and other properties tested.

This is what Argosim has introduced in their STIMULUS offering. It’s a mechanism for specifying requirements, testing them for correctness and consistency, and then generating tests from them that can be used in future validation testing.

At present, the workflow is somewhat disconnected from existing flows; ideally, requirements would be specified using STIMULUS – that’s Argosim’s long-term vision. For the moment, it’s more of a collaborative process.

First, a requirements engineer will create natural-language requirements in the same way as is done today. He then hands them off to a verification engineer, who will create a model in STIMULUS using a formal language that can then be simulated. Both requirements and assumptions are included in the description. Through simulation, problems might be identified – and the original requirements engineer is then consulted for discussion and correction.

If no issues are identified, then the verification engineer can generate tests that will be used downstream to close the loop and ensure that the implementation of the requirements matched the intent. If tests aren’t generated, or if the test set is incomplete, then this is still something of an open-loop process.

You can find out more about STIMULUS in their announcement.

Leave a Reply

featured blogs
Sep 25, 2020
[From the last episode: We looked at different ways of accessing a single bit in a memory, including the use of multiplexors.] Today we'€™re going to look more specifically at memory cells '€“ these things we'€™ve been calling bit cells. We mentioned that there are many...
Sep 25, 2020
Normally, in May, I'd have been off to Unterschleißheim, a suburb of Munich where historically we've held what used to be called CDNLive EMEA. We renamed this CadenceLIVE Europe and... [[ Click on the title to access the full blog on the Cadence Community site...
Sep 24, 2020
I just saw a video from 2012 in which Jeri Ellsworth is strolling around a Makerfaire flaunting her Commodore 64-based bass guitar....
Sep 24, 2020
Samtec works with system architects in the early stages of their design to create solutions for cable management which provide even distribution of thermal load. Using ultra-low skew twinax cable to route signals over the board is a key performance enabler as signal integrity...

Featured Video

Latency-Optimized PAM-4 Architecture for Next-Generation PCIe

Sponsored by Synopsys

This video presentation briefly describes how DesignWare® IP for PCIe® 5.0 is minimizing risk and accelerating time to market, and what Synopsys is doing to help designers prepare for next-generation PAM-4 PCIe 6.0 designs.

Click here for more information about DesignWare IP Solutions for PCI Express

Featured Paper

Helping physicians achieve faster, more accurate patient diagnoses with molecular test technology

Sponsored by Texas Instruments

Point-of-care molecular diagnostics (PoC) help physicians achieve faster, more accurate patient diagnoses and treatment decisions. This article breaks down how molecular test technology works and the building blocks for a PoC molecular diagnostics analyzer sensor front end system.

Read the Article

Featured Chalk Talk

AVX Supercapacitors: PrizmaCap

Sponsored by Mouser Electronics and AVX

If your application requires a supercapacitor, there are a lot of options. You need the right form factor, temperature range, weight, and capacitance, of course. In this episode of Chalk Talk, Amelia Dalton chats with Eric DeRose of AVX about choosing the right supercapacitor and about PrizmaCap - a new supercapacitor with low height, high temperature, and lightweight.

Click here for more information AVX PrizmaCap™