Page 51 - EE Times Europe Magazine | April2019

EE|Times EUROPE — Boards & Solutions Insert 51

Adapting the Microcontroller for AI in the Endpoint

With viable competitors to Arm now out
there, including the up-and-coming
instruction-set architecture offered by the
RISC-V foundation, why did Eta Compute
choose to use an Arm core for ultra-low-
power machine-learning acceleration?
“The simple answer is that the ecosystem for The architecture of
Arm is just so well-developed,” Eta Compute GreenWaves’ GAP9
CEO Ted Tewksbury told EE Times Europe. ultra-low-power AI
“It’s just much easier to go to production [with chip now uses 10
Arm] than it is with RISC-V right now. That RISC-V cores.
situation could change in the future … RISC-V (Image: GreenWaves)
has its own set of advantages; certainly, it’s
good for the Chinese market. But we’re looking
primarily at domestic and European markets That capability, in the right hands, may impossible or it was going to cost you a
right now with the ecosystem for [our device].” also offer the opportunity to reduce power fortune. And the fortune it was going to cost
Tewksbury noted that the major challenge consumption. you was essentially your investor’s money
facing the AIoT is the breadth and diversity Eta Compute can’t take advantage of it just going to a different company, and that is very
of the applications. The market is rather yet, because the new policy does not apply difficult to justify.”
fragmented, with many relatively niche retroactively to existing Arm cores, so it is not GreenWaves’ custom extensions alone give
applications commanding only low volumes. applicable to the M3 core that Eta is using. its cores a 3.6× improvement in energy con-
Altogether, however, this sector potentially But could Tewksbury see Eta Compute using sumption over unmodified RISC-V cores. But
extends to billions of devices. Arm custom instructions in future product Croome also said that RISC-V has fundamen-
“The challenge for developers is that they generations to cut power consumption fur- tal technical benefits that are simply due to
cannot afford to invest the time and the ther? “Absolutely, yes,” he said. its being new.
money in developing customized solutions “It’s a very clean, modern instruction set;
for each one of those use cases,” Tewksbury ALTERNATIVE ISAs it doesn’t have any baggage,” he said. “So
said. “That’s where flexibility and ease of use RISC-V has been getting a lot of attention this from an implementation perspective, the
become absolutely paramount. And that’s year. The open-source ISA allows the design RISC-V core is actually a simpler structure,
another reason why we chose Arm — because of processors without a license fee, whereas and simple means less power.”
the ecosystem is there, the tools are there, designs based on the RISC-V ISA can be pro- Croome also cited control as an important
and it’s easy for customers to develop prod- tected as with any other type of IP. Designers factor. The GAP8 device has eight cores in its
ucts quickly and get them to market quickly can pick and choose which extensions to add, compute cluster, and GreenWaves needs very
without a lot of customization.” including their own customized extensions. fine, detailed control over the core execution
After keeping its ISA under lock and key for French startup GreenWaves is one of sev- to allow maximum power efficiency. RISC-V
decades, Arm finally announced in October eral companies using RISC-V cores to target enables that, he said.
that it would allow customers to build their the ultra-low–power machine-learning space. “In the end, if we could have done all of
own custom instructions for handling spe- Its devices, GAP8 and GAP9, use eight- and that with Arm, we would have done all of that
cialist workloads such as machine learning. nine-core compute clusters, respectively. Each with Arm; it would have been a much more
device also has an addi- logical choice … because no one ever got fired
tional core that handles for buying Arm,” he joked. “The software tools
control functions. are there to a level of maturity which is far
Martin Croome, vice higher than RISC-V … but, that said, there’s
president of business now so much focus on RISC-V that those tools
development at Green- are increasing in maturity very fast.”
Waves, explained to In summary, while some see Arm’s hold
EE Times Europe why on the microprocessor market as weakening,
the company uses RISC-V in part because of increased competition
cores. from RISC-V, the company is responding by
“The first reason is allowing some customized extensions and
RISC-V gives us the ability developing new cores designed for machine
to customize the cores at learning from the outset.
the instruction-set level, In fact, there are both Arm and non-Arm
which we use heavily,” devices coming to the market for ultra-low-
said Croome, adding that power machine-learning applications. As
the custom extensions are the TinyML community continues to work
used to reduce the power on reducing neural network model size
of both machine-learning and developing dedicated frameworks and
and signal-processing tools, this sector will blossom into a healthy
workloads. “When the application area that will support a variety of
company was formed, if device types. ■
Eta Compute’s ECM3532 uses an Arm Cortex-M3 core plus you wanted to do that
an NXP CoolFlux DSP core. The machine-learning workload with any other processor Sally Ward-Foxton is a staff correspondent
can be handled by either or both cores. (Image: Eta Compute) architecture, it was either at AspenCore.

www.eetimes.eu | APRIL 2020