Google Project Ara And The Low-Power Imperative

Project Ara also raises intriguing design questions both near and long term.


You’ve no doubt seen the slides: 50 billion Internet of Things (IoT) devices by 2020. That’s an amazing number, but consider this: What if they each draw 1W?

All things begin equal, we’d have to build another 50 nuclear power plants in the world to handle that additional energy requirement. (Something tells me that outcome is unrealistic).

Power takes center stage as we evolve into the IoT era and specifically the mobile devices so central to IoT. How do we deliver what we need to deliver and not have to build a bunch of nuclear power plants?

This question is worth pondering in the context of Google’s Project Ara, the so-called “Lego” smart phone architecture unveiled in April.

The tradeoffs
Project Ara’s design considerations are intriguing because the architecture can enable a new way of designing for mobile while overcoming power challenges at the same time.

Project Ara, which was initiated at Motorola Mobility, uses the MIPI Alliance UniPro and M-PHY protocols as the backbone for a modular electronics architecture inside a smart phone “endoskeleton.” Using electro-permanent magnets (they don’t need a permanent charge to keep the bond), designers and consumers can affix various functional modules to build a customized smart phone—say, one with special radios or more-powerful imagers or other sensors.

MIPI UniPro won the business because it enables the tunneling of multiple communications protocols within the system. Layer 1/1.5 include the M-PHY and PHY adapter; Layer 2, the data link layer offers error correction among other features; Layer 3, includes ID-based switching; Layer 4 is the transport layer interface to the application. In short, UniPro is optimized for mobile applications and scalable from single link to full network.

UniPro’s unique opportunity
David Rutledge, chief technologist at Lattice whose FPGAs are being in leveraged in the Project Ara prototype, as–among other things–the programmable interface for UniPro, said:

“Project ARA is using it exactly as intended:  high-speed communications of multiple protocols. It’s a good application of the technology and it’s exactly why UniPro was built. I think it’s a major endorsement of the UniPro standard.”

What’s intriguing to me long term is the very philosophy that Project Ara evokes for other applications outside smart phones: Taking a low-power, high-bandwidth backplane and making it the focus of modular, customizable design. And for some IoT-related markets, it’s almost like we don’t have a choice.

“Nobody is going to put 50 billion devices around the world if they’re drawing 1W of power each,” said Rutledge. “Those each better be 10microwatts or 100milliwatts in standby and a few milliwatts in active states.”

Said Arif Khan, product marketing director with Cadence: “Chip designers will need to understand the implications of using UniPro for system connectivity. As this is not widely used as yet, there will be a learning curve.”

Expanding IP opportunity
For now, expect renewed interest in MIPI and other IP, soft and hard, Khan said. If the module market takes off, the number of design starts will rise, potentially leading to increased IP consumption.

“IP makers will renew their commitment to the mobile chip space with increased emphasis on low power designs and technology,” he added.

Lattice’s Rutledge, however, sees plenty of opportunity for FPGA makers since each module contains a standard interface to the backplane:

“On one side is MIPI UniPro. On the other side is the module developer’s playground. Who knows what they’re going to want to do? It’s a perfect place to allow people to innovate. It’s an ideal opportunity for FPGAs.”

As for the modular approach to electronic systems design, Lattice’s Rutledge said we’re seeing it already.  A device teardown may identify a number of ICs in a given smart phone, but they’re really modules, he said.

“They’re pre-built systems in an SIP that provide dedicated functionality–WiFi, antenna management or touchscreen management modules. People don’t recognize that. The module ecosystem is developing like the IP ecosystem and over time different standards will evolve,” Rutledge added.

Some UniPro resources include:

Project Ara also raises intriguing design questions both near and long term.

  • Hank Walker

    50B IOT devices @ 1 W each is <5% of US electrical generating capacity. Presumably some of those 50B devices are smart lighting systems, smart thermostats, etc., that will achieve a net reduction in energy consumption. Of course, one would expect IOT devices to spend most of their time sleeping at microwatt power.

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