Bluetooth Smart radios join the shopping revolution

June 16, 2015 OpenSystems Media

Retailers can capitalize on this ultra-low power technology to enhance the shopping experience and maximize profits.

Bluetooth-enabled smartphones and tablets are now the constant companions of many consumers, including those that shop regularly in retail malls. As it’s now possible to track shoppers within malls and within individual stores using Bluetooth electronic beacons, this has created an opportunity for retailers to deliver sales messages – advertising to them when they’re most likely to be responsive.

As one provider of this technology puts it, “Target your customers with personalized recommendations, in real-time, at the perfect moment to encourage purchase.” The market for such services is expected to grow from $8.12 billion in 2014 to nearly $40 billion by 2019, according to analyst MarketsandMarkets. Other services include indoor navigation, asset tracking, and mobile payments.

If they decide to engage with the technology, consumers can be confident that they won’t miss a shopping opportunity. They can choose to have their phones switched on, or to run the apps that respond to the electronic messages that retailers push at them. Consumers must have Bluetooth switched on and allow for push messages, so they remain in control. The retailers benefit from a low cost, context-aware way to deliver sales offers. Perhaps more importantly, they can gather and analyze data about customer journeys – physical journeys through their stores and commercial journeys that capture buying habits. When that data becomes available for thousands of customers, the information becomes very powerful, which is the essence of big data.

In almost every instance, the technology that underpins this revolution is Bluetooth Low Energy, often referred to as Bluetooth Smart. The same technology is also found in proximity tags that send an alert to your smartphone or other receiver when you come within range.

Bluetooth has been with us for decades, but what’s now known as Classic Bluetooth is too power-hungry for beacon applications, which need to operate for months, if not years, on one coin cell if they are to offer the required “place and forget” deployment capability. Bluetooth Smart radios are built into battery-powered, stand-alone beacons that broadcast advertising messages to shoppers as they come within range, typically somewhere between 5 m and 50 m of the beacon.

Key design criteria for beacons are that the infrastructure around them doesn’t restrict where they can be placed, so they need to be small and unobtrusive. And, as with most consumer electronic devices, low cost is crucial.

Bluetooth Smart differs from Classic Bluetooth in a number of important ways that make it an attractive option for beacons (also shown in Figure 1):

  • Classic Bluetooth radios typically draw around 40 mA at 3 V, but best-in-class Bluetooth Smart radios producing 0 dBm output (a power level suited to most beacon applications) can draw less than 5 mA at 3 V while still offering a 50 m range in many environments
  • Average power consumption in some applications may be only 1 percent compared top Classic Bluetooth, due to the relatively long periods during which a Bluetooth Smart device will be in sleep mode
  • Wake up time is just 6 ms, versus around 100 ms for Classic Bluetooth
  • It can send authenticated data in just 3 ms, versus up to 1 second for Classic Bluetooth
  • It offers 128-bit banking-level (AES-128) security to keep data safe


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Figure 1: Comparison of Bluetooth Classic and Bluetooth Smart.
(Click graphic to zoom)

Not all Bluetooth Smart implementations are created equal

Despite the energy savings promised by Bluetooth Smart, how the technology is implemented can have a dramatic affect on system energy consumption and battery life. The primary criteria for choosing a Bluetooth Smart radio system-on-chip (SoC) to form the heart of a beacon are peak current consumption, energy consumption over time (considering the requirements of the application), receiver sensitivity (the beacons need to receive a signal from your smartphone to know that you’re in range), and the ability to work from one small battery. In real-world applications, battery life will also depend on the advertising interval, or how often the beacon is required to transmit data, so when comparing device data, you need to ensure that the operating conditions under which the figures are quoted are the same, or at least very similar.

To gain a more detailed understanding of how energy is consumed while a beacon is operating, you must determine the charge consumed versus time for each advertising operation. These parameters include:

  • The advertising interval and charge per ad
  • The time taken and charge consumed from cold boot until the first ad
  • The time, peak current, and charge consumed by each of the three advertising channels normally used

Also, you need to consider the processor resources that may be available for application code within the Bluetooth Smart SoC. If it’s possible to produce a completely hosted solution without resorting to an external microcontroller, this will again save design time, cost, and space.

In selecting a Bluetooth Smart radio, other important considerations are sometimes overlooked. Functional integration will determine how many external components are needed to create the beacon. The fewer you need, the less design effort that’s required and the lower the end product’s cost. Fewer components also means you can make smaller, more reliable products. Design effort is also reduced if the Bluetooth Smart vendor offers a reference design and proven software.

Bluetooth Smart beacon reference design

Dialog Semiconductor’s DA14580 SmartBond SoC integrates a Bluetooth Smart radio with an ARM Cortex-M0 processor core and intelligent power management. The processor and on-chip peripherals are accessible via up to 32 GPIOs (Figure 2). Excluding any current limiting resistors needed for buzzers or LEDs, the beacon reference design needs only 12 external components: six capacitors, a 16 MHz crystal, three inductors, and three resistors. Using the reference design, the battery life is calculated as 178 days when advertising every 0.7 seconds. Advertising every 5 seconds extends this to 730 days, or two years.


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Figure 2: The Dialog Semiconductor DA14580 simplified block diagram.
(Click graphic to zoom)

The Bluetooth tags and beacons market is forecast to grow at over 25 percent per annum over the next four years. Those products that succeed will be those that are small, reliable, and offer a combination of lowest cost-of-ownership and longest battery life. When selecting an integrated circuit to power a Bluetooth Smart beacon, examine the specifications of competing parts in details to gain an in-depth understanding of how they are likely to perform in a given application.

Mark de Clercq is a Product Manager at Dialog Semiconductor. Previously he was a design engineer at Phillips Electronics and held research and teaching posts at McGill University, where he received his Masters degree in Microelectronics. He has also studied strategic marketing at the Harvard Business School.

Mark de Clercq, Dialog Semiconductor
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