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Thread Connected Hangers in a Parisian Boutique


We take a look at how a new product using the Thread mesh protocol and the Nordic nRF52840 SoC is helping an upmarket Parisian clothing store improve its customer experience.

Galeries Lafayette is an upmarket French clothing retailer. Its store on the famous Champs-Élysées in Paris is now home to more than a thousand connected hangerers, enhancing the customer experience and creating a more efficient store.

The solution from BLUEGRioT includes 2,600 clothing hangerers each equipped with a Nordic nRF52840, an RFID reader and a small display. When a customer picks up an item, they can select a size from the display and a member of staff will bring it to them, wherever they are in the fitting room or elsewhere in the store.

Much more than a fancy gadget

While at first glance a connected hangerer may seem frivolous, there’s a lot going on here.


Paris has no shortage of high-end boutiques, so Galeries Lafayette needs to do something special to stand out in the minds of luxury buyers. Putting the latest technology at the core of the customer experience is one way to do just that. While the young French company BLUEGRioT developed the system, it was Galeries Lafayette themselves that first proposed the idea.

Read more: The Connected Technologies Saving Physical Retail

There’s benefits to the store beyond the customer experience, though. Firstly, the concept means less items need to be out on display, improving the selection on display and/or reducing clutter.

Thanks to sensors inside the hanger, it knows what item of clothing is attached. The device records how many times per day the item has been touched and the number of times the hanger has been removed from the rack. This data is sent to the store system once per day. Over time, such data gives Galeries Lafayette a lot of useful information on the in-store experience, allowing them to draw their own conclusions about the popularity of certain items and trends.


Combining innovation with aesthetics

To achieve a demanding technical solution while also meeting the store’s high demands for design was a challenge the young team relished.

“We have studied and developed custom electronics, incorporating the latest sensor technologies, and RFID & Thread communication. The discreet use of the LEDs and the screen gives the hanger a sober and elegant appearance, but just touching it brings to life a magical interface,” explains CTO & co-founder of BLUEGRioT, Rudy Houque.

The innovation doesn’t stop with the in-store components. BLUEGRioT monitor and manage the Thread mesh network from their office using the nRF52840 Development Kit and a Raspberry Pi.

The team has designed a custom dashboard using open-source tool Grafana to monitor the health of the network:


One important element is the battery monitoring. Each evening, the store is automatically sent a list of hangers that should be charged overnight, using a custom-built solution at the store.

Choosing Thread, and choosing Nordic

Thread was their first choice because of the high number of nodes required. Around 1,500 are in use at any one time and they communicate via 13 Thread routers.

Read more: An Introduction to Thread

Because of the screen and RFID reader in each hangerar, power consumption was the main challenge during design. It’s one of the reasons for choosing to transmit data once per day when the store is closed. During the same connection, any firmware updates take place.

The need to conserve power also influenced the system design: “We tried detaching from the radio and then waking the device up only when someone touches the hangerar, but the delay was a little too long for the premium experience we were trying to create. So they function as Sleepy End Devices. As soon as the hanger goes to sleep, it sends a simple message every couple of minutes to stay in the network,” explains Rudy.

BLUEGRioT took advantage of the nRF5 SDK for Thread and Zigbee during the development process. Rudy says he met Nordic at CES and liked what he saw:

“When we started the company we bought an evaluation board and got easy-to-access help from the DevZone forums. We’ve had a similar experience on the Thread forums too. We’ve especially enjoyed using the Nordic development tools like the Power Profiler Kit, and also the nRF Thread Topology Monitor.”


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