Wireless Heart Rate Monitor Uses Nordic Bluetooth Low Energy SoC

A Chinese manufacturer of smart wearables, Wearpai Technology Co., Ltd has used Nordic Semiconductor’s award-winning Bluetooth Low Energy (Bluetooth LE) nRF52832 System-on-Chip (SoC) in its ‘K1’ wearable. The wearable is designed for OEMs and enables developers with limited RF design experience to efficiently monitor heart rate values using photoplethysmography, a technique which employs green and infrared LEDs to measure the varying absorption of light as blood flows in the wrist region.

The K1 device can also provide real-time analysis of other physiological parameters and physical activities like tracking calories, sleep patterns, steps, and walking/running distance, enabling OEM developers flexibility to select parameters that are important for their target audience. Moreover, the wearable displays the time, date, and messages/caller ID when wirelessly linked to a smart phone. Either the IP68-waterproof smart bracelet or the user’s smart phone can be used to locate the other device.

By using Wearpai Technology’s open Application Programming Interface (API), developers can customize applications for the K1, as well as create branded iOS and Android mobile apps to suit their own requirements. From the smart phone, users can also access more detailed information about their physical condition via Wearpai Technology’s Wearfit 1.0 or Wearfit 2.0 companion app. Supported by low power consumption characteristics of the Nordic SoC, the K1’s rechargeable Lithium-ion battery can last for approximately one week or up to 10 days in low power mode.

Nordic’s nRF52832 Bluetooth LE SoC, a member of Nordic’s sixth generation of ultra low power (ULP) wireless connectivity solutions, combines the 64MHz, 32-bit ARM Cortex M4F processor with a 2.4 GHz multiprotocol radio (supporting Bluetooth 5, ANT, and proprietary 2.4 GHz RF software) featuring -96 dB RX sensitivity, with 512 kB Flash memory and 64 kB RAM. When launched, the SoC was the world’s highest performance single-chip Bluetooth LE solution.

The SoC is supplied with Nordic’s S132 SoftDevice, a Bluetooth 5-certified RF software protocol stack for building advanced Bluetooth LE applications. The S132 SoftDevice supports Central, Peripheral, Broadcaster, and Observer Bluetooth low energy roles, supporting up to twenty connections, and enabling concurrent role operation.