Development of Bluetooth® Low Energy Beacon Device for the "otta" Personal Monitoring Service

Case Study: Bluetooth® low energy Solution [Interview with developers: otta Part 2]

"otta" is currently drawing attention as a new type of monitoring and locator service. In line with the commencement of its commercial operation from the spring of 2017, a new tracking device utilizing a Bluetooth low energy beacon (BLE beacon) also made its debut. The beacon is an example of IoT (Internet of Things) technology. Today we present the interview content between developers involved in this project, regarding challenges that had to be overcome and demands for the BLE solution that had to be met.

Otta, Tessera, Renesas

Case Study Details

Developing a new type of BLE beacon tracking device for commercial service

Signals from a Bluetooth low energy (subsequently "BLE") beacon device carried by children are picked up by receiving stations located all over town and smartphones carried by adults, to enable location monitoring of the children. Harnessing IoT (Internet of Things) technology to create a truly community based network for watching and protecting children, this is the concept behind the new monitoring service "otta" which began commercial operation in early 2017.

Here we invited Fumikazu Yamamoto, president of otta Inc. as well as others involved in the development, including staffs from Renesas Electronics Corporation (subsequently "Renesas"), the company that provided the BLE solution, and Tessera Technology Inc. (subsequently "Tessera"), the company that supported the development of BLE beacon device. We interviewed the participants about the various challenges and requirements that had to be resolved, and present their answers and comments below.

"otta" President Yamamoto (center) and others involved in the development of the BLE beacon tracking devices got together to talk about the development back story.

Before we start, here is a brief overview of the development of BLE beacon device.

The otta company began a trial project using BLE beacon devices positioned as mass production prototypes in May 2015. Commercialization goals were formulated at the beginning of 2016 with the initial launch of the commercial business scheduled for early 2017. It was also decided to create a new BLE beacon device to coincide with the commercial launch. The main concept points for the new terminal, as defined by Yamamoto in 2016, were as follows.

  • Provide a security whistle to replace the security buzzer
  • Adopt a thin long shape resembling a security whistle
  • Develop customized BLE components rather than using a commercially available module, to achieve further reduction in costs compared to the trial prototype
  • Realize battery life for at least 1 year (beacon transmission cycle: 1 second)
  • Use a battery type that is easily to find (sold in convenience stores)
  • Projected initial order volume: 200,000 units
  • Realize mass production in time for the commercial service launch in early 2017

A chance encounter

- We heard that it was a struggle to find a development partner for mass production of BLE beacon devices for your commercial service to be launched in the beginning of 2017.

Fumikazu Yamamoto (otta): Because we wanted to use whistle type instead of the traditional buzzer type, therefore, a slender shape and smaller BLE module than before had become necessary. But finding such a module indeed turned out to be not easy. As we were looking at an initial production run of 200,000 units, I thought that creating a custom board should work from a cost related standpoint. I therefore contacted BLE chip vendors, but none showed interest, and the commercially available modules that we were offered instead of a chip were not suitable in terms of size and cost.

At that point, an acquaintance of mine who had seen the demonstration of a 1-yen coin sized BLE module at a Renesas event suggested that I talk to them, since a module of that size would fit into a thin, long terminal.

The newly developed BLE beacon tracking device

Figure 1: The newly developed BLE beacon tracking device "otta.w"

Jun Uehara (Unit 1 Section Chief, Japan Sales Dept. 4, Global Sales Division, Industrial Solution Business Unit, Renesas): It was in April 2016 that I was first approached by Yamamoto. Besides providing BLE module solutions, Renesas also offers BLE chip solutions to customers and partners with appropriate technological capabilities. After hearing Yamamoto's explanation of the intended development concept, I proposed using the RL78/G1D microcontroller with integrated BLE RF transceiver which seemed most suitable.

At the same time, I also introduced Yamamoto to our partner company Tessera who had participated in the "IoT Subcommittee" that had developed the 1-yen coin sized BLE module prototype that was seen by Yamamoto's acquaintance.

Yamamoto (otta): We realized that it would just be possible to fit the RL78/G1D chip solution into a whistle shaped terminal and therefore decided to go ahead with this. So it all began with that chance encounter.

The product that got the ball rolling: 1-yen coin sized BLE module developed by the

Figure 2: The product that got the ball rolling: 1-yen coin sized BLE module developed by the "IoT Subcommittee", and a wearable terminal in wristwatch form using the module, shown at "Renesas DevCon OSAKA 2016"

Prototype completed half year later

- After deciding to use the chip, what was your development schedule?

Yamamoto (otta): After the initial consultation, we worked out the specifications together with Tessera, a process that was completed in June 2016. We then embarked on the design development. By September of 2016, we had a prototype in hand.

- That's quite a rapid pace.

Yamamoto (otta): Yes, because we had decided on launching the commercial service at the beginning of 2017, we tried to move the development process along as quickly as possible. In effect, it took only about half as long as the development of the terminal for the trial system. But then, we were quite convinced from the beginning that Tessera would be able to deliver speedy results .

Koji Eguchi (Sales Section, Sales Division, Tessera Technology Inc.): Because the time to specification lock-in and the development period were shorter than usual, we did have some doubts, to be honest, whether we could finish in time. But we had developed a demonstration product using the RL78/G1D in the context of the "IoT Subcommittee," so we already had some know-how related to BLE and various wireless terminals, and we therefore weren't seriously worried.

- What were the factors that enabled you to complete the development quickly?

Shintaro Ito (Deputy Manager, Product Planning and Development Section, Sales Department, Tessera): The fact that we had an actual achievement in development through our work with the "IoT Subcommittee" was a major factor. Also, software development usually is one of the main areas prone to delays, but in the case of the RL78/G1D, the division between hardware and software was clear-cut. Hardware and software development proceeded side-by-side, which helped to speed up the process.

With regard to the new terminal, functions such as beacon, remaining battery status and OTA (Over The Air) updating were required, but the software stacks and software development manuals for realizing these functions were already available at Renesas. I can say for sure that without these, development and mass production would not have been possible in such a short time.

Eguchi and Ito from Tessera

Eguchi and Ito from Tessera

Looking for a battery that's easy to replace

- What was the most troublesome aspect of development?

Yamamoto (otta): We had the longest discussions about which battery to use.

Ito (Tessera): Yes, the battery question indeed came up repeatedly and was explored in quite some depth. Making the battery life longer requires higher capacity which in turn means a bigger battery. Initially, we considered using four LR44 cells. As the RL78/G1D has an operating voltage range of 1.6 to 3.6 V, this would have allowed driving it without a step-up circuit but it would not have given us enough capacity. We also considered using four SR44 cells with higher capacity. However, although the SR44 battery is quite common in hearing aids and therefore available at larger electrical supply stores, it is not available at convenience stores. In the end, we gave priority to availability and selected a size N (IEC LR1) which is available at convenience stores, but it does require a step-up circuit.

- In aiming to develop a terminal that would be easy to use for anyone, reducing cost presumably also was a major consideration?

Yamamoto (otta): Yes, regarding the cost, we were able to shave more than one third off the cost of the trial system terminal, which means that we achieved our initial target.

- What measures did you take to reduce costs?

Ito (Tessera): Various measures such as sourcing components in bulk were undertaken, but the high integration of the RL78/G1D chip itself was a major contributing factor for reduced costs. The fact that fewer peripheral parts are required than with other BLE chips not only keeps parts costs lower, it also means that fewer assembly and testing steps are required and that quality assurance is easier. All of this proved very beneficial for the bottom line.

- To which degree could peripheral parts costs be reduced?

Koichi Sato (Wireless Products Department, Industrial A & P Business Division, Broad-Based Solution Business Unit, Renesas): The RL78/G1D incorporates a matching circuit for antenna connection (balun circuit) and a DC-DC converter which conventionally are realized with external components. The balun circuit in particular requires considerable design know-how. Having it built-in therefore not only helps to reduce costs but also makes board design easier.

Benefits of integrated antenna matching circuit (balun)

Figure 3: Benefits of integrated antenna matching circuit (balun)

More than one-year battery life

- Did you clear the "more than a year battery life at a beacon transmission cycle of 1 second" requirement?

Ito (Tessera): We designed the battery life to last around 14 to 15 months.

Yamamoto (otta): We are now past the half-year mark since the launch of the commercial service, but so far we have had not a single report regarding battery failing. The RL78/G1D consumes only about half the power of the BLE chip we used earlier, so I don't think we need to worry about battery life.

Sato (Renesas): The RL78/G1D also features very low current consumption when transmitting (4.3 mA at 0 dBm). And fortunately we just had completed a beacon mode software stack for the RL78/G1D by the time otta decided on using the chip.

Because this beacon mode stack is purpose-designed for transmission only, preparation for reception operation can be omitted, resulting in about 50% lower power consumption when used as beacon device. This contributes to the long battery powered operation of the terminal.

Renesas representatives Uehara and Sato

Renesas representatives Uehara and Sato

Looking towards the future

- Tell us about the outlook for the "otta" personal monitoring service and your further development plans for tracking devices and similar.

Yamamoto (otta): Since June 2017, a community testing project for elementary school students and elderly people is under way in Shibuya Ward, and the expansion of our service area is set to continue. We therefore expect the first lot of 200,000 units to run out sometime during 2018.

With regard to the tracking device, the current whistle type is designed for children, but we are also in the process of developing a terminal with functions and a shape design more suited to the elderly. Of course we are again working together with Tessera and Renesas on this.

And in regard to the service itself, which currently is mainly operating in such a way that it provides information that the monitored person has arrived at a certain location, we are planning to expand this, for example with predictive and preventive alerts based on a learning capability that will realize when the monitored person is taking longer than usual for a given journey.

I envision a world where it will be commonplace for "otta" beacon devices to be distributed at school entrance ceremonies nationwide.

otta President Yamamoto

"otta" President Yamamoto

More Information for Renesas Bluetooth Low Energy Solutions

Easy & Versatile Connectivity

As a solution compatible with Bluetooth Low Energy technology, Renesas offers small modules that can also use microcontroller peripheral functions. It adopted RL78/G1D, the lowest power consumption microcontroller in the industry and is an excellent energy saving item.

In the following material, you can see the overview, evaluation tools, application example for beacon… etc. of “small size/energy saving/Bluetooth Low Energy compatible microcontroller RL78/G1D" introduced in this article.

To know the development story of this BLE beacon device, the product that started otta commercial service, and how BLE solution worked in this application, click on below link:

otta Part 1: IoT Technology Drives Bluetooth® Low Energy Solution Enhancing the "otta" Personal Monitoring Service

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