Bluetooth Smart: Doing (A Lot) More With Less

Can we get to Bluetooth without batteries?


By Charles Dittmer and Prithi Ramakrishnan

I was really struck by Ann Steffora Mutschler’s piece last month (Running Out Of Energy?).

She notes that by 2040, the energy required for computing is expected to surpass the estimated world’s energy production. That’s a problem.

One factor could be the rise of IoT applications. Billions of devices will be deployed in the next decade, and we can’t build enough power plants to support them all.

Fortunately, the industry never stops innovating–from materials, to devices, and system power optimization. I’m thinking here about companies like Ambiq Micro, which offers sub-threshold microcontrollers and real-time clocks. This kind of engineering is testing those dire long-range energy forecasts (or even medium-range forecasts for that matter).

But when it comes to IoT, there’s another wrinkle. The utility and value of these systems is increasingly tied to their ability to communicate with the outside world: capture data through sensors, make sense of that data locally and then transmit it along for additional analysis in the cloud.

Billions of batteries?

The industry rallied around Bluetooth as one of those communications standards, and Bluetooth Smart (Bluetooth Low Energy, or BLE) is driving power consumption to new lows. For all of these devices, there remains a system-design challenge.

Generally, energy to power these systems needs to be captured and stored. That raises another major question: Should billions of IoT devices — using harvested energy or otherwise — have to have billions of batteries? How should we think about this as we confront the need to integrate communications into these systems in the hopes of driving their ubiquity?

There are two ways of dropping a radio into these IoT systems. With the ‘build-in-house’ route, you have a design team with RF capability, and you may have some existing components you’ve done over time. However, you’re going to have to be current with the standard and modify your design to reflect that. Then you’re going to have to be able to do the integration within the device, build the latest software/stack and then get that qualified. For some companies, adding Bluetooth Smart functionality to a device is such a huge differentiator that they feel the need to have this RF design talent within their company.

Leveraging the ecosystem

The second approach is to purchase Bluetooth Smart IP blocks and assemble the pieces yourself. In this scenario, you don’t need a full RF design team, and there are advantages in time to market. But there are disadvantages in integrating IP from multiple third parties along with internally designed blocks. In the case of ARM, you get an end-to-end pretested solution.

For teams that can drive their radio IP down below 1V, their overall solutions can function at 1V, taking advantage of different 1-volt battery-size topologies and energy-harvesting techniques.

We’ve demonstrated an ARM Cordio BT4 Bluetooth Smart test chip that uses a small zinc/air hearing aid battery. Running at 1V, the micro-beacon has a battery life of more than two years.

Getting to a point where you have a good radio that can connect to these devices and not have to have a battery connected opens up a lot of design possibilities (not to mention cuts costs). It opens up applications such as labels, remote sensors, and other devices—areas outside of what we have traditionally known as Bluetooth.

And think about an existing market with new possibilities: The industry may ship 200 million smart phones, but there’s the potential to ship 400 million Bluetooth ear buds with them. It’s not just about the audio at that point: You can get blood pressure, pulse, oxygen level, all that stuff along with the audio features and phone connectivity for sound and speaking. The real wearable could be a hearable.

So, you can imagine the possibilities. And the industry is definitely on a path to overcome many of these low-power design challenges to enable not only these transformative products but to keep us from straining the world’s energy capacity.

Charles Dittmer is ARM wireless technical marketing manager. Prithi Ramakrishnan is ARM wireless product manager. This piece was based on a joint presentation they gave at Bluetooth World 2016.