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BLE Smart Health Band: Architecture, Working, Hardware Design

By RF Wireless Expert Team

A BLE Smart Health Band combines a low power microcontroller, Bluetooth Low Energy radio, sensors, display, battery and power-management circuitry and embedded firmware to deliver connected wearable functions while managing a limited energy budget. This article explains how a BLE Smart Health Band works and covers its architecture, major hardware components, communication flow, firmware design and key engineering considerations. The band or watch design is similar except the mechanical layout & design.

The watch or band typically communicates with a smartphone or other central device using BLE advertising, connection procedures and GATT services and characteristics for structured data exchange. Designing a Smart Health Band therefore requires coordination between BLE architecture, hardware selection, RF design, sensor integration, power optimization, GATT services, firmware architecture, security and mobile device connectivity.

Working of BLE based Smart Health Band Architecture

BLE Smart Health Band

The figure depicts generic architecture of BLE Smart Health Band use case. Typically Smart Health Band houses sensors, BLE SoC, display, User Interface (keys or buttons) and battery. Following steps describe working of this BLE compatible Smart Health Band system.

  • Sensors mounted on the Smart Health Band collect health/fitness data and MCU processes it.
  • Data is sent via BLE to smartphone using standard profiles (e.g. heart rate, health thermometer, battery service etc.).
  • The smartphone app installed shows real time data and also syncs with the cloud for long term tracking and insights.

Typical Specifications of Smart Health Band or Smartwatch (Example : MI Smart Band 5)

NoTech SpecMI Smart Band 5
1PPG Heart rate sensorYes
2SpO2 sensorNo
3GyroscopeYes (3-Axis)
43-Axis accelerometerYes (3-Axis)
5Rotor Vibration motorNo
6DisplayAMOLED
7Screen Size2.79cm
8Touch screenYes
9Resolution126 x 294
10ButtonYes
11BluetoothBLE 5.0
12BatteryLipo 125mAh
13Charging time2 Hour
14Stndby time15 Days
15Body MaterialPolycarbonate
16Strap MaterialThermoplastic polyurethane
19System requirementAndroid 5.0 or above
20System requirementiOS 10.0 or above
21Sport mode11
22Step countingYes
23Sleep checkingYes
24Water Resistant5 ATM
25All day heart rateYes
26Sedentary reminderYes
27ClockYes
28TimerYes
29CountdownYes
30NotificationYes
31Find phoneYes
32WeatherYes
33Charging statusYes
34OTA upgradeYes
35Remote music controlYes
36Weight12gram
37Charging typeMagnetic

BLE Smart Health Band or Smartwatch Hardware Design

The common components which can be used for such smart health band design are as follows.

  • BLE SoC and MCU Combined (nRF54L15 or nRF54L10 or nRF52840)
  • MAXM86161A integrates photodiode, LED drivers, optical AFE, 19-bit ADC and ambient light cancellation.
  • TI AFE4950 has integrated wearable biosensing AFE supporting synchronized PPG + single lead ECG acquisition.
  • Low Power Accelerometer (Bosch BMA530/BMA580 family, ST LIS2DUXS or KX122)
  • Use ADI MAX30208 sensor for skin temperature measurement.
  • AMOLED display (0.95 inch size)
  • 1000 mAh LiPo Battery

Note : ADI’s MAXREFDES103 reference design specifically combines MAX32664 + MAX86141 for wrist based HR, SpO₂, HRV, respiration and sleep related algorithms. Refer features of MAXREFDES103 reference design >>.

Summary

The choice of hardware components and design of smart health band or smartwatch depends on desired features planned to be incoporated on it. Commonly available smart band manufacturers are Realme, Redmi, Noise, Huawei, Honor, MI, Samsung etc.

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