Interview with Andreas Willig

Compact real-time specialists

22. Juni 2022, 7:00 Uhr | Tobias Schlichtmeier
TQMxX4XxL series currently comes in six different processor versions
© TQ-Group

Real-time is becoming increasingly important for embedded applications. But what exactly is real-time? And how do developers find the right basis for their application? Questions we put to Andreas Willig, Product Manager of TQ-Group.

How do you define real-time?

Andreas Willig: Getting reliable results in a maximally predetermined time. When it comes to embedded, we‘re speaking of milliseconds or even shorter time spans.

What trends do you see influencing the real-time systems market?

Willig: It‘s the decentralized and distributed controls that are becoming increasingly significant – and that in different areas of application, like industrial or building automation, plus transportation and safety. Field buses with real-time capability and TSN-enabled Ethernet are important elements of the trend. Plus security of course – without which networked solutions are vulnerable.

Andreas Willig from TQ Group
Andreas Willig, Product Manager of TQ-Group: „You can‘t get into security early enough.“
© TQ-Group

Doesn‘t that call for fast clocked, expensive special processors?

Willig: Fast clocking and costly – that‘s the way it used to be. Today you find attractively priced processors with specialized cores like the Arm Cortex-R5, used in the new Am64xx and Am243x Sitara processors from Texas Instruments. It makes real-time easy for edge applications.

And how does it do it?

Willig: The R5 core comes with a special, so called tightly coupled memory (TCM). It avoids the unpredictable access behavior of caches, and the program code in this memory always has the same time to execute. Added to that you get timed deterministic interrupt handling implemented directly in hardware and independent of software.

Isn‘t just faster clocking enough?

Willig: Fast enough isn‘t automatically the same as deterministic. What if – for whatever reason – it isn‘t fast enough? You shouldn‘t risk that. Plus you get an overhead that you don‘t want in an embedded area.

What do you mean by that?

Willig: Faster means more effort, more power consumption, means more cooling investment, higher costs, larger scale and heavier – all the things you don‘t want for embedded. Thanks to the Sitara AM64xx and AM243x real-time specialists, we can produce the pin-compatible modules of the TQMxX4XxL series with just 38 by 38 mm in size and passively cooled. To meet the need for functional safety there‘s also an isolated Cortex-M4 core with its own memory and I/Os to provide the necessary safety independently of the other cores.

What about real-time-capable communication?

Willig: Thanks to integrated programmable real-time units (PRUs) of the MCU/CPU, the modules feature flexible industrial communication skills, including complete protocol stacks for EtherCAT slave, Profinet device, EtherNet/IP adapter and IO Link master. Plus you have capability for Gigabit Ethernet and TSN-based protocols. And the PRUs enable additional interface functions in a system on chip, including sigma-delta decimation filter and absolute encoder interfaces. Overall the modules support up to four Gigabit Ethernet ports with real-time capability, two normal GbE ports, two CAN FD interfaces, and as many as nine UARTs. In addition you have timers and pulse-width modulators. There is also no lack of general interfaces: USB 2.0, SerDes lane, USB 3.1, PCIe with integrated PHY, SDIO, I2C, SPI and SD card can all be configured.

When it comes to networking there‘s always the „insecurity“ of security.

Willig: That‘s something you can‘t look into early enough. If you want to add security in your project at the end, you will lose a lot of time and security gaps will crop up. It‘s best to look into security right away when starting a development. That‘s the reason why, additionally to the functions integrated in processors for our modules, there‘s an optional secure element offering an end-to-end security chain right from the start.

What trends do you see coming in the real-time environment?

Willig: With more computers at the edge, the environment will become more heterogeneous, the performance classes and functional demands increasingly different. Our new TQMxX4XxL series consequently comes in six processor versions matching different demands. What makes this possible is that processor developers like Texas Instruments design their series more and more fine granular for lower-cost coverage of differing demands. For hardware developers that means increasing effort to keep up – but with modules you can cleverly thwart the growing complexity.

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