Electronic Labeling Takes Off

One hit product for the Internet of Things (IoT) market is the electronic shelf label (ESL). The ESL is rapidly replacing the paper price labels on store shelves throughout Europe and Asia, as well as within retail giants such as Walmart in the United States.

But why are retailers replacing nearly zero cost paper labels with an electronic widget that sells for on the order of $5 each (pricing in multiple quantities found on Alibaba.com)? The simple reason is that shoppers, armed with smart phones, have real time information of the price and availability of a product listed online. Brick-and-mortar retailers want them to shop the store rather than point and click. Being able to offer the same product in store for the same price as found on-line means retailers can now begin to compete with on-line giants.

To provide some measure of how rapidly this transformation from paper to plastic is occurring, Samsung CEO Chi-Joon Choi said at the Equipmag 2014 trade show in Paris last September, “ESL will be a huge market as a management innovation tool and internet of Things tool, and a part of our lives tools.”

Edison Investment Research, in a research note issued January 2014, puts some numbers to Samsung CEO’s statement by listing the major retailers installing ESL solutions and the number of outlets they were outfitting: Casino Guichard Perrachon SA (12,038 outlets), Walmart (10,773), Carrefour (9,994) Tesco—a Samsung win (6,984), Delhaize Group (3,451), Metro (2,243), and Les Mousquetaires (2,242). The majority of these retailers already have installed, or are installing, ESL solutions from Store Electronic Systems SA headquartered in Nanterre, France (western suburb of Paris). The research note estimates the potential market size to be around 140 million labels in food retail alone.

What does an ESL provide that makes retailers willing to pay the higher cost of each? The ESL displays product information, price, and in some cases a marketing message on the shelves of retailers, which can be changed instantly. For example, the price of slow moving perishables can be reduced to avoid being wasted. But the real power of the ESL is in changing shoppers’ engagement with the store. Carrefour in Villeneuve la Garenne (a suburb north of Paris) added near-field communications to the ESL and provides its shoppers with a smart phone app that enables the phone to display information about the product as well as capture pricing information. With a shopping list entered into the app, upon entering the store the shopper is directed to every item on the list. The shopper also can receive additional information on any product from the ESL using NFC.

The major benefit to the store is getting an understanding of customer shopping behavior and providing the kinds of services in store that shoppers receive in point and click sites online.

A liquid crystal display or other technology, such as electronic paper attached to the front edge of a retail shelf, displays the product information. Controlling this display is a microcontroller and an RF radio linking the ESL to the store’s central server via a gateway. While some ESLs receive power from the shelves, others must operate on coin cell batteries and that need to run for at least five years on a charge. Thus the microcontroller in this ESL IoT chip not only has to be power efficient, it has to provide high compute performance if features cited in the Carrefour example are to be realized.

Most of the R&D for existing CPU IP cores designed in the past 20 years or so have been aimed at developing high-end CPU architectures with long pipelines and high clock rates, with power savings built around partitioning the design into power islands that could be regulated to minimize power drain. That was appropriate for the smart phones and tablets selling in the hundreds of millions, but completely out of sync with the demands of ultra low power IoT devices. In a CPU IP company that has directed its R&D at providing bigger and faster, it’s hard to redirect the engineering mentality to small pipeline cores that runs in 10s of MHz of clock frequency. One company that has developed a CPU IP core built to provide high performance with small pipelines and extremely low power is Andes Technology. Andes is targeting the IoT opportunity with its 21st century CPU architecture.

For example, a 60-MHz AndesCore N801 core with 128KB of eFlash has been designed into an ESL device that communicates over a sub-GHz frequency band and will run for five years on a single coin cell battery. How does the core achieve high performance while still maintaining long battery life? Two features illustrate how this is possible: PowerBrake and FlashFetch. The first reduces power while the second helps save power and contributes to enhanced performance in the 3-stage pipeline CPU

PowerBrake achieves lower power by stalling the processor proportionally. For example a 60MHz processor stalled 66 percent of the time (2 out of 3 cycles). Thus, it will have an effective frequency of a 60/3=20 MHz. A simple task can be run at a PowerBrake mode with effective frequency at 20 MHz, while a complex task can be run at full clock with other tasks given the clock rate appropriated for their complexity. FlashFetch is a small amount of cache that sits between the main memory cache and the CPU pipeline. It provides the CPU core with instructions at full clock frequency while reducing the amount of power-hungry accesses to flash.

As the ESL example demonstrates, IoT devices bring the unique computing requirement of high performance and ultra low power operation. Existing CPU cores built for the high volume smart phone and tablet markets are not a good solution. Having a new architecture designed from the start with high performance functionality with ultra low power capability is the solution that serves the IoT requirement best.