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Inside a Beacon – Part 1 – The Physical Beacon

This is part 1 of a 3 part series that explains what’s inside a beacon. In this part we take a look at the physical beacon.

All beacons are similar inside because they are based on standard circuit designs from Nordic Semiconductor, Dialog Semiconductor or Texas Instruments. These semiconductor manufacturers produce a complete system on a chip (SoC) that requires minimal external components. The SoC is a small computer with memory that runs software created by the manufacturer of the beacon. We will take a deeper look at the SoC in part 2 and the software in part 3.

For this series of articles we going to take a deeper look at Minew’s i7 beacon. It’s based on Nordic Semiconductor’s nRF52832 SoC.

Minew i7

Inside the case is a PCB with a CR2477 slide in battery at the rear.

Inside the i7

The main chip you can see is the mRF52832. At the top you can also see the antenna that’s created using a track in the printed circuit board. The holes at the bottom right are connections used to program the beacon.

To understand more, we need to look at the printed circuit board design and circuit schematic:

i7 design
Circuit diagram – click to see larger in new window

It can be seen that there aren’t many external components. Y1, the metal component at the top is the crystal used to maintain timing. The SoC has a number of programmable input/output (PIO) pins that are multi-purpose. In a beacon some are usually connected to LEDs and a switch as shown at the left hand side of the circuit diagram. There are also capacitors that need to be external to the SoC.

U2, U3 and U4 are optional for this beacon and missing from this variant of the i7. U2 is the KX022-1020 accelerometer. U3 is the SHT31 temperature/humidity sensor. U4 is the BH1721 light sensor.

In part 2 we take a closer look at the nRF52 SoC.

Bluetooth Sensor Beacons For Prognostics

If you are considering using Bluetooth sensor beacons for prognostics, you should take a look at the free IEEE paper IoT-Based Prognostics and Systems Health Management for Industrial Applications (pdf).

Prognostics is the determination of health of assets to diagnose anomalous behaviour and predict the remaining useful life. It’s used to:

  • Prevent catastrophic failures
  • Increase asset availability through less downtime and less time wasted through ‘no fault found’ tests
  • Extend maintenance cycles
  • Execute timely repair

The overall aim is to lower lifecycle costs via fewer inspections, repairs and manual inspections. It can be applied to all types of assets across all sectors but is particularly applicable to manufacturing, industry and infrastructure. Infrastructure includes roads and ports as well as utility industries such as water, power and gas.

Prognostics and in-situ testing isn’t new. However, what is new is substantially improved viability and economics. New sensors, such as beacons, are easier to use, can be attached to legacy equipment and have much lower costs. The cost of connectivity and cloud storage is also decreasing. This means more assets can be retro-actively connected and the sharing of data across assets and platforms enables a more complete operating picture. This opens up new business opportunities.

The paper explains the four main types of prognostic management strategies: corrective, fixed-interval preventative, failure-finding, and condition-based maintenance (CBM). It also explains a new fusion approach to prognostics:

The paper gives examples of use of prognostics in the manufacturing, heavy industry, energy generation, transport & logistics, infrastructure assets, automobile, medical, warranty and robotic industries.

It ends with the mention that, in the future, current research and work on energy harvesting will benefit sensors used for prognostics.

More information:

Sensor Beacons
Beacon Proximity and Sensing for the Internet of Things (IoT)
Beacons in Industry and the 4th Industrial Revolution (4IR)
Using Bluetooth Wireless Sensors

Latest Nordic WirelessQ Magazine Available

Beacons are small computers with a complete System on a Chip (SoC). There are four main companies that manufacturer SoCs: TI, Dialog, NXP and Nordic. Nordic is the most popular SoC for use in beacons, mainly because of the lower (tool) license cost and ease for beacon manufacturers developing the software (actually called firmware) that runs in the beacons.

Nordic has a new free Wireless Quarter Magazine that showcases uses of Nordic SoCs in many types of device, not just beacons.

Learn about:

  • Gartner research showing sensor innovation fosters IoT growth
  • Beacons help U.S. shoppers find way
  • Bluetooth LE in Amazon FreeRTOS
  • Bluetooth LE smart textiles on the rise
  • Article combining Bluetooth Low Energy and LPWANs
  • Firmwave’s use of Bluetooth Low Energy beacons to build an inexpensive satellite broadcast system
  • Article on Getting started with Bluetooth mesh

Read more

New Minew G1 Bluetooth Gateway Video

Minew has a new video showcasing the G1:

The G1 gateway collects advertising data from iBeacon, Eddystone, Bluetooth LE sensor and other Bluetooth LE devices and  sends it to your server by HTTP(S) or MQTT/ using WiFi or Ethernet.

More information:

Available Gateways
Beacon Proximity and Sensing for the Internet of Things (IoT)
Beacons in Industry and the 4th Industrial Revolution (4IR)

Resurgence of Beacons in Retail

The demise of Google Nearby prompted some commentators to declare the death of beacons. However, here at BeaconZone we are actually seeing a resurgence of the use of beacons in retail.

Gone are the unsolicited notifications and gone are the ‘get rich quick’ marketers. The scenarios that remain tend to use beacons as an adjunct to something else rather than being the main solution itself. For example, they are used to provide triggering in CloseComm‘s WiFi onboarding app used by Subway, McDonalds, BurgerKing and CircleK and NCR.

Beacons are being rolled out to many food retailers, particularly in the USA. They are also taking new physical forms as witnessed by Mr Beacon:

If you are looking for more innovative uses of beacons in retail, take a look at Alibaba’s Fashion AI concept store as mentioned in the latest Wired (UK):

RFID and Beacons are used to detect items picked up during shopping so that customers can collect what they have looked at, have accessories automatically selected and view what’s in stock. Once they are home, a virtual wardrobe allows customers to buy anything they saw in store.

Beacons can also be used to enable audit compliance. Eric West, Head of Strategy at IMS has a useful free pdf on takeaways from GroceryShop, the retail industry conference. The pdf also mentions the use of beacons in lighting to drive location-based messages and wayfinding. Also:

“Amazon’s 2017 acquisition of WholeFoods was a “tipping point” that ensured all grocery players were speeding up their digital plans.”

Read about Beacons for Marketing

Wiliot To Enable New Beacon Usecases

We mentioned Wiliot last March and since then their R&D team has created early engineering samples that prove it’s possible to create a battery-less Bluetooth LE beacon harvesting energy from radio frequencies (RF).

The Wiliot device looks more like a RFID tag than a traditional beacon in that it’s supplied as a very thin PVC inlay sheet containing the chip and wire antenna together. The thin form factor, no battery and the relatively low cost will allow it to be manufactured into or stuck onto clothing and packaging that will provide for many new usecases.

Producing such a device isn’t easy as it can’t use existing System On a Chip (SoC) devices as produced by Nordic, Dialog and Texas Instruments (TI) because they are too large and use too much power. Wiliot has had to create their own SoC from the ground up, including software tools to develop and program the devices. We have been told it will be a year before Wilot has all the components in place for commercial rollout. Meanwhile, selected organisations can join the Early Advantage Program (EAP). There’s a new a product overview (PDF below) that explains the EAP and the main usecases, connected packaging, connected apparel, logistics and asset tracking:

Wiliot already have Early Advantage Program (EAP) agreements in place with over a dozen brands including top fashion brands, a telco, appliance companies, a furniture brand and packaging companies.

Machine Learning Accountability

AI machine learning is a great partner for sensor beacon data because it allows you to make sense of data that’s often complex and contains noise. Instead of difficult traditional filtering and algorithmic analysis of the data you train a model using existing data. The model is then used to detect, classify and predict. When training the model, machine learning can pick up on nuances of the data that a human programmer wouldn’t see by analysing the data.

One of the problems with the AI machine learning approach is that you use the resultant model but can’t look inside to see how it works. You can’t say why the model has classified something some way or why it has predicted something. This can make it difficult for us humans to trust the output or understand what the model was ‘thinking’ when the classifications or predictions end up being incorrect. It also makes it impossible to provide rationales in situations such as ‘right to know’ legislation or causation auditing.

A new way to solve this problem is use of what are known as counterfactuals. Every model has inputs, in our case sensor beacon data and perhaps additional contextual data. It’s possible to apply different values to inputs to find tipping points in the model. A simple example from acceleration xyz sensor data might be that a ‘falling’ indicator is based on z going over a certain value. Counterfactuals are generic statements that explain not how the model works but how it behaves. Recently, Google announced their What-If tool that can be used to derive such insights from TensorFlow models.

Read about Machine Learning and Beacons

Advertising Change Stream

If you work in IT and particularly if you have knowledge of programming, you will know it’s best to be informed of data rather than repeatedly request changes.

Repeatedly requesting changes, called polling, wastes resources when there’s no data returned. It also doesn’t get the data as soon it is available as you have to wait for the next poll.

A feature of our BeaconServer™ and BeaconRTLS™ is that they offer change stream data on all database data. Change stream is a standard web (HTTP(S)) protocol that provides data to systems and apps as and when it becomes available. The client sets up a long running HTTP connection and then receives updates.

The stream looks something like:

First you get an ‘ok’ followed by data as and when it becomes available. The above only shows a generic iBeacon. When used with sensor beacons this also includes all decoded data such as movement, temperature, humidity, air pressure, light and magnetism (hall effect), proximity (short range IR and PIR) and fall detection.

BeaconServer™ and BeaconRTLS™ provide REST based insert, update, query and change stream on all data allowing external systems and apps to fully use the system. This can also be authenticated via HTTP header tokens to prevent unauthorised access.

An example of use of the change stream is BeaconRTLS™ itself. The web UI uses the change stream to asynchronously update the UI with no flicker or redraw. All data, including beacons, locations and alerts are obtained asynchronously from the server (image below not live at it needs login):

Experiment Before Committing

We see some companies only after they have gone a long way down a particular road only to discover they made a big mistake early on. It might be, for example, they have heavily committed to the wrong beacon, wrong platform or have assumed something on one of the mobile platforms. They didn’t do their research. Often we can help them get on the right track but sometimes not.

At the other end of the research scale we have other companies who ask us “Will beacons work in an xyz environment?” where xyz has ranged, for example, from underground on the tube for the police to inside cars for a car retailer. Taking this further, we also get many, what we call, “armchair entrepreneurs” who want to work everything out before even looking at a beacon.

While we have a lot of expertise and provide advice through consultancy, it’s often the case that there are some aspects that are unknown until things are tried for real in the actual environment. Wireless solutions can be very fickle.

A lot can be learned about beacons, Bluetooth and the environment by buying one inexpensive beacon and trying things out. In the case of software, try implementing a thin slice through the proposed system touching on the perceived risky or unknown areas. Experiment before committing. Don’t go all in buying thousands of beacons and commissioning full custom software until you are confident things will work.

Consider a Feasibility Study

Beacon Battery Level Observations

Most beacons provide a battery level % indication that’s visible in advertising and/or the manufacturer configuration app. It’s also usually visible via a Bluetooth Service Characteristic.

Some observations:

  • Lithium batteries (if you are using them) have a very flat voltage profile with a sudden drop off towards the end of their life.

Here’s an example for Energizer Lithium AA:

For a typical CR2032 Lithium coin cell:

  • The beacons use very little power over time. If you are measuring over days when batteries last years, you will see very little difference.
  • The firmware in the beacon and/or app need to determine what voltage signifies 100%. This can vary by battery type. Some beacons/apps simplify things by using a fixed voltage for 100% such that it’s possible that the voltage is higher than this at the start of the life of the battery. The level will appear to stay at 100% for a long time.

A consequence of the above factors is that you can’t estimate battery life by looking at battery percentage over time. You need to measure current use. We have a previous blog post on this topic.

Battery level can only be used as an indication that the battery is low and should be changed.