Bluetooth LE employee ID tag enables low latency personnel tracking and contact tracing

Nordic Semiconductor today announces that TagBox, a Bengaluru, India-based technology company, has selected Nordic’s nRF52840 Bluetooth® 5.2/Bluetooth Low Energy (Bluetooth LE) advanced multiprotocol System-on-Chip (SoC) to power its ‘Tag360-ID’ contact tracing employee ID tag solution. 

Tag360-ID is a 43 by 22 by 72mm Bluetooth LE wearable identification card, designed to enable real time location tracking and contact tracing of on-site personnel (such as employees, facility visitors, or contract staff) across indoor and outdoor facilities of all sizes, including hazardous environments and restricted zones. 

Proximity event recording

Using the Nordic SoC-enabled Bluetooth LE connectivity and Received Signal Strength Indication (RSSI) capability, Tag360-ID can monitor its proximity to and determine interactions with other Tag360-ID ID cards, and/or Bluetooth 4.0 (and later) smartphones running the iOS/Android ‘TagStaff’ app. Each Tag360-ID scans for other Tag360-ID devices in its vicinity and based on the RSSI signature and duration of the contact, records ‘contact events’ between tags. In these scenarios, social distancing alarms and hotspots can also be generated in real time. Each Tag360-ID can record up to 8,000 proximity events—in relation to other Tag360-IDs—using the on-tag memory, which is supported by the Nordic SoC’s generous 1MB Flash and 256kB RAM memory allocation. To aid contact tracing and establish sanitization measures, physical assets at a facility can also be tagged with a ‘TagHop’ sensor to record when employees come in contact with specific equipment. 

The Bluetooth LE connectivity provided by the Nordic SoC allows all contact events to be relayed to a proprietary ‘TagHub’ gateway (which also employs Nordic’s nRF52840 SoC). The aggregated data is then sent over cellular or Wi-Fi networks to the Cloud for contact event information and analytics to be viewed through the associated ‘BoxLens™’ Cloud-based platform. When the TagStaff companion app is used, contact events are relayed directly to the BoxLens platform without relying on the presence of a TagHub gateway. From the Cloud platform, local site supervisors, employee health and safety teams, and management can then track each person’s contact history and ascertain social distancing violations at a facility, enabling intelligent site response and quarantine protocols in a disease-spread scenario – for example a confirmed positive case of Covid-19. 

The nRF52840 SoC’s Bluetooth 5 Long Range capability enables contact tracing applications over extended distances at larger facilities, allowing the Tag360-ID solution to detect a higher number of social distancing violations in real time. Nordic’s nRF52840 provides full Bluetooth 5 support including 2x on-air raw data bandwidth (2Mbps); 4x range; 8x broadcasting ability with advertising extensions that increase the advertising packet payload size to 251 bytes, and an improved channel coexistence algorithm. 

The Tag360-ID uses the nRF52840 SoC’s powerful 64MHz, 32-bit Arm® Cortex® M4 processor with floating point unit (FPU) for algorithm data processing and to support the tag’s built-in 3-axis accelerometer, which determines whether or not personnel are carrying the ID card. If no activity is detected for more than 15 minutes, a warning is issued indicating the ID card is not being carried by the individual. TagBox anticipates companies and facilities will use the same Tag360-ID sensors for asset tracking use cases, with the built-in accelerometer used for shock and motion detection. Coupled with the Tag360 suite of sensors, which also use Nordic SoCs, the complete solution will have the ability to provide 360-degree monitoring of products, assets, and staff in a supply chain. For example, this capability is crucial to monitor cold chain compliance and traceability of Covid-19 vaccines. 

The Tag360-ID uses a CR2477 1000mAh Li-Ion battery to provide battery life of one year before replacement, even with a contact tracing scan frequency of 15 seconds. This endurance is achieved thanks in part to the ultra-low power characteristics of the nRF52840 SoC, which has been engineered to minimize power consumption with a fully-automatic power management system that reduces power consumption by up to 80 percent compared with the nRF51 Series.

The nRF52840 SoC’s Arm Cortex M4 processor is combined with a 2.4GHz multiprotocol radio (supporting Bluetooth 5.2, ANT™, Thread, Zigbee, IEEE 802.15.4, and proprietary 2.4GHz RF protocol software). A new radio architecture with on-chip PA provides features -95dBm RX sensitivity (at 1Mbps Bluetooth LE), a maximum output power of 8dBm, and a total link budget of 103dBm. The nRF52840 SoC is supplied with Nordic’s S140 SoftDevice, a Bluetooth 5.2-certified software protocol stack for building long range and high data throughput Bluetooth LE applications. Nordic’s unique software architecture includes a clear separation between the RF protocol software and the developer’s application code, simplifying development and ensuring the SoftDevice doesn’t get corrupted when developing, compiling, testing, and verifying the application code. The S140 SoftDevice offers concurrent Central, Peripheral, Broadcaster, and Observer Bluetooth LE roles, and supports high throughput and long range modes as well as advertising extensions. 

Bluetooth Long Range capability

“One of the key reasons we selected Nordic’s nRF52840 for Tag360-ID and the TagHub gateway was the SoC’s Bluetooth Long Range capability, which is important for contact tracing applications over extended distances on construction sites and shop floors,” says Sameer Singh, Co-founder and VP Engineering of TagBox. 

“In addition, the nRF52840’s generous memory allocation makes it possible to capture more contact events, even when the gateways are not nearby, for example in parking areas or outside the facility.”

• About TagBox
• About nRF52840
• About Nordic Semiconductor