Smart lock offers many unlocking options including secure Bluetooth LE and NFC connectivity

01-07-2019 | Nordic | Subs & Systems

Nordic Semiconductor has announced that Shenzhen Lumi United Co Ltd has selected the company's nRF52840 Bluetooth5/Bluetooth LE advanced multiprotocol SoC to give the wireless connectivity for its 'Xiaomi Mijia' smart door lock.


The smart lock is intended for both commercial and domestic applications, and once installed can be paired to a Bluetooth 4.0 (and later) smartphone or tablet. From the 'Mi Home' app, the user can configure the lock and remote alarms, examine a history of when the lock has been opened, plus unlock the Xiaomi Mijia. From the main interface of the app, clicking on the lock icon will immediately unlock the door using Bluetooth LE wireless connectivity.


The Nordic SoC includes an Arm TrustZone CryptoCell-310 cryptographic module and an AES 128-bit hardware accelerator. These options support a broad variety of asymmetric, symmetric, and hashing cryptographic services for secure applications, assuring the security of the unlocking process. The smart lock can also be unlocked using NFC via the nRF52840 SoC'son-chip NFC-A tag and a user's NFC-compatible smartphone. It also supports alternative unlocking options, which include fingerprint, password, and emergency key unlocking.


The company's nRF52840 multiprotocol SoC is their most advanced ultra-low power wireless solution. The SoC supports complex Bluetooth LE and other low-power wireless applications that were not possible previously with a single-chip solution. The SoC combines a 64MHz, 32-bit Arm Cortex M4F processor with a 2.4GHz multiprotocol radio (supporting Bluetooth 5, ANT, Thread, Zigbee, IEEE 802.15.4, and proprietary 2.4GHz RF protocol software) together with 1MB Flash memory and 256kB RAM. A new radio architecture with on-chip PA offers features -95dBm RX sensitivity (at 1Mbps Bluetooth LE), a maximum output power of 8dBm, and a total link budget of 103dBm. The chip supports all the features of Bluetooth 5compared with Bluetooth 4.2.


"Although other wireless protocols were an option, Bluetooth LE was more suitable as it is not only faster but also provides a better experience and satisfies our need for stability," says Tao Liu, Lumi product manager."We selected the nRF52840 SoC both for its range and ultra-low energy consumption. The maximum output power of 8dBm provides much greater connection range, while the low power consumption extends the battery life of the door lock."

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