editor's blog
Subscribe Now

Safe Processing

When we recently looked at software and hardware safety standards, much of the discussion was focused on process-oriented standards like DO-254 and DO-178. But we also mentioned some other standards without going into detail. And some of those operate on the concept of “safety integrity level,” or SIL.

The origin of this concept is IEC 61508, which establishes four SILs, numbered 1-4, with 4 indicating the “safest” level. The determination of SIL appears to be relatively complex and somewhat ambiguous since the specific failure modes must be identified for each individual system, and are not codified in IEC 61508. They involve both process considerations as well as the Probability of Failure on Demand, or PFD,  (or its inverse, the Risk Reduction Factor, or RRF).

It’s actually pretty easy to understand the PFD ranges for each SIL: it’s the maximum number of zeros after the decimal for the PFD (or the minimum number of zeros in the RRF). So SIL 1 applies to a PFD of 0.1 to 0.01 (or an RRF of 10 to 100); SIL 4 applies to a PFD of 0.0001-0.00001 (or an RRF of 10,000-100,000).

ISO 26262 has a similar concept for automobiles, referring to Automotive SILs, or ASILs.

Only systems can achieve a SIL level; components may tout a SIL level, but simply using such components (or a process known to have achieved a certain SIL level on a different product) is not sufficient to demonstrate that SIL level. So, for instance, when TI just announced their Hercules microcontrollers, they didn’t say that “these  microcontrollers conform to SIL x.” They listed a series of features that are specifically designed to help a designer achieve a desired SIL or ASIL.

Because these standards don’t call out specific functional requirements, only probabilities of failure and process requirements, the feature list itself can’t be expressly correlated with specifics of the standard. Again, they’re simply things that are known to allow the implementation of safer systems.

More details and the specific features can be found in TI’s release

Leave a Reply

featured blogs
Jul 5, 2022
The 30th edition of SMM , the leading international maritime trade fair, is coming soon. The world of shipbuilders, naval architects, offshore experts and maritime suppliers will be gathering in... ...
Jul 5, 2022
By Editorial Team The post Q&A with Luca Amaru, Logic Synthesis Guru and DAC Under-40 Innovators Honoree appeared first on From Silicon To Software....
Jun 28, 2022
Watching this video caused me to wander off into the weeds looking at a weird and wonderful collection of wheeled implementations....

featured video

Demo: Achronix Speedster7t 2D NoC vs. Traditional FPGA Routing

Sponsored by Achronix

This demonstration compares an FPGA design utilizing Achronix Speedster7t 2D Network on Chip (NoC) for routing signals with the FPGA device, versus using traditional FPGA routing. The 2D NoC provides a 40% reduction in logic resources required with 40% less compile time needed versus using traditional FPGA routing. Speedster7t FPGAs are optimized for high-bandwidth workloads and eliminate the performance bottlenecks associated with traditional FPGAs.

Subscribe to Achronix's YouTube channel for the latest videos on how to accelerate your data using FPGAs and eFPGA IP

featured paper

3 key considerations for your next-generation HMI design

Sponsored by Texas Instruments

Human-Machine Interface (HMI) designs are evolving. Learn about three key design considerations for next-generation HMI and find out how low-cost edge AI, power-efficient processing and advanced display capabilities are paving the way for new human-machine interfaces that are smart, easily deployable, and interactive.

Click to read more

featured chalk talk

Reduce Power System Needs with Multichannel Power Monitors

Sponsored by Mouser Electronics and Microchip

Power monitors can be very effective in terms of power management for a variety of designs and the use of a multichannel power monitors can not only lower your overall system power but also lower your code overhead, simplify prototyping and event detection. In this episode of Chalk Talk, Amelia Dalton chats with Mitch Polonsky from Microchip about the benefits of multichannel power monitors and how Microchip’s PAC194x and PAC195x can help you monitor your power in your next design.

Click here for more information about Microchip Technology PAC194x & PAC195x Monitors