Nordic Semiconductor nRF52840
Smart Fitness Wellness Wristband
Aperçu
A mid-range custom PCB smart wristband featuring BLE, NFC, health and motion sensors, and a small touchscreen powered by a rechargeable Li-Po battery.
silei linArchitecture système
MCU
POWER
SENSOR
MODULE
DISPLAY
ACTUATOR
- BATTERY → POWERPowerLi-Po battery connected to PMIC input/output
- POWER → MCUPowerMain regulated 3.3V supply to MCU
- POWER → SENSOR_PPGPowerLow-noise regulated 1.8V supply for optical sensor
- POWER → SENSOR_IMUPowerRegulated 1.8V supply for IMU
- MCU → SENSOR_PPGI2CI2C bus control and interrupt line for heart rate data
- MCU → SENSOR_IMUI2CI2C bus control and motion interrupt line
- MCU → SECURE_ELEMENTI2CSecure element communication for payment transactions
- MCU → DISPLAYSPIHigh-speed SPI interface for AMOLED display updates
- MCU → HAPTICPWMPWM control signal for haptic vibration motor driver
Nomenclature
| Référence | Type | Composant | Fabricant | Boîtier | Qté | Fiche technique | Correspondance |
|---|---|---|---|---|---|---|---|
| NRF52840-QIAA-R7 | MCU | Nordic Semiconductor nRF52840 Main system microcontroller, handles BLE stack, NFC quick pairing, and sensor data processing | Nordic Semiconductor ASA | 73-VFQFN Dual Rows, Exposed Pad | 1 | Correspondant | |
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| WPR1500-LDO | POWER | Texas Instruments BQ25150 Manages Li-Po battery charging, provides low-noise LDO rails for analog sensors and MCU | NXP USA Inc. | — | 1 | Correspondant | |
Afficher les 4 alternatives étudiéesprojects.detail.aiVerified | |||||||
| ASR00003 | POWER | Rechargeable Li-Po Battery 150mAh Primary power source for the smart wristband | TinyCircuits | — | 1 | Correspondant | |
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| MAX30101EFD+T | SENSOR | Analog Devices MAX30101 Optical heart rate monitoring, SpO2, and pulse detection for sleep tracking | Maxim Integrated Products, Inc. | — | 1 | Correspondant | |
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| BMI270 | SENSOR | Bosch BMI270 Motion tracking, step counting, gesture detection, and sleep movement analysis | Bosch Sensortec GmbH | LGA-14 | 1 | Correspondant | |
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| T/ | MODULE | STMicroelectronics ST33 Secure element for encrypted contactless payments and token storage | Industrial Seating Inc. | — | 1 | Correspondant | |
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| DISPLAY | DISPLAY | AMOLED Display Panel with Driver Visual user interface for status, workout data, and notifications | 3M Electronic Specialty | — | 1 | Correspondant | |
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| DA7280-00FVC | ACTUATOR | Linear Resonant Actuator (LRA) Driver Provides haptic feedback and silent alarms | Dialog Semiconductor GmbH | QFN-12 | 1 | Correspondant | |
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Guide de fabrication
6-8 hoursAdvanced
1
Procurement & Preparation
- Source all required electronic components including NRF52840-QIAA-R7 MCU, BQ25150 PMIC, MAX30101, BMI270, ST33, DA7280-00FVC, AMOLED display, and 150mAh Li-Po batteries (ASR00003).
- Prepare custom PCB stencils and inspect Gerber files for the smart wristband mainboard, ensuring proper clearance for the 1.8V and 3.3V power rails, I2C pull-up resistors, and SPI display routing.
2
Hardware Assembly & Wiring
- Apply lead-free SMT solder paste onto the custom PCB pads using a stencil printer, placing the nRF52840 MCU, BQ25150 PMIC, MAX30101 sensor, BMI270 IMU, ST33 secure element, and DA7280-00FVC LRA driver via pick-and-place machine.
- Run the populated PCB assembly through a convection reflow oven with a standard lead-free temperature profile.
- Manually solder the AMOLED display flex cable to the board SPI interface (SCK, MOSI, CS, DC, RESET, GND) and connect the 150mAh Li-Po battery (ASR00003) to the BAT+ and BAT- power pads.
3
Firmware Setup
- Flash the Nordic Semiconductor nRF52840 bootloader and application firmware via SWD interface, configuring the BLE stack and NFC quick pairing parameters.
- Integrate peripheral drivers for I2C communication with the MAX30101 heart rate sensor, BMI270 IMU, and ST33 secure element, alongside SPI drivers for the AMOLED display and PWM configuration for the DA7280 haptic driver.
4
Testing & Calibration
- Perform electrical and power-rail testing using a multimeter and oscilloscope, verifying that the BQ25150 outputs clean VDD_3V3 and VDD_1V8 rails and that charging functionality operates correctly with the 150mAh Li-Po battery.
- Calibrate the MAX30101 optical sensor for heart rate and SpO2 accuracy, test the BMI270 motion tracking and step counting algorithms, verify NFC secure payment transactions with the ST33 secure element, and test UI responsiveness on the AMOLED touchscreen.
Document
smart wristband
A mid-range custom PCB smart wristband featuring BLE, NFC, health and motion sensors, and a small touchscreen powered by a rechargeable Li-Po battery.
Design Overview
| Item | Details |
|---|---|
| Product Type | smart wristband |
| Key Functions | heart rate monitoring, sleep tracking, motion tracking, contactless payments, quick pairing |
| Power Source | Rechargeable Li-Po Battery |
| Connectivity | Bluetooth LE (BLE), NFC |
| Size | Standard fitness tracker form factor with small OLED/AMOLED touchscreen |
| Environment | wearable |
| Difficulty | Advanced |
| Est. Time | 6-8 hours |
System Architecture
Power Topology: A 3.7V rechargeable Li-Po battery feeds the BQ25150 PMIC, which generates a primary 3.3V rail for the nRF52840 MCU, secure element, and haptic driver, alongside ultra-low-noise 1.8V LDO rails dedicated to the optical PPG sensor and IMU to minimize analog measurement jitter.
Module List
| Module ID | Type | Name | Function | Voltage |
|---|---|---|---|---|
| MCU | MCU | Nordic Semiconductor nRF52840 | Main system microcontroller, handles BLE stack, NFC quick pairing, and sensor data processing | 3.3V |
| POWER | POWER | Texas Instruments BQ25150 | Manages Li-Po battery charging, provides low-noise LDO rails for analog sensors and MCU | 3.7V |
| BATTERY | POWER | Rechargeable Li-Po Battery 150mAh | Primary power source for the smart wristband | 3.7V |
| SENSOR_PPG | SENSOR | Analog Devices MAX30101 | Optical heart rate monitoring, SpO2, and pulse detection for sleep tracking | 1.8V |
| SENSOR_IMU | SENSOR | Bosch BMI270 | Motion tracking, step counting, gesture detection, and sleep movement analysis | 1.8V |
| SECURE_ELEMENT | MODULE | STMicroelectronics ST33 | Secure element for encrypted contactless payments and token storage | 3.3V |
| DISPLAY | DISPLAY | AMOLED Display Panel with Driver | Visual user interface for status, workout data, and notifications | 2.8V |
| HAPTIC | ACTUATOR | Linear Resonant Actuator (LRA) Driver | Provides haptic feedback and silent alarms | 3.3V |
Key Components
8/8 modules matched to real parts. See the BOM tab for the full component table.
Nordic Semiconductor nRF52840 (NRF52840-QIAA-R7)
Candidate 1 (NRF52840-QIAA-R7) is an exact match for the searched part number and includes comprehensive alternative dis
Texas Instruments BQ25150 (WPR1500-LDO)
Although none of the candidates explicitly reference the BQ25150 chip in their titles, candidate 2 (WPR1500-LDO) include
Rechargeable Li-Po Battery 150mAh (ASR00003)
Candidate 1 (ASR00003) directly matches the searched part number for the TinyCircuits lithium ion battery pack.
Build Summary
- Difficulty: Advanced
- Estimated time: 6-8 hours
- Tools required: Inventory Management System, ESD-safe bins, CAD Software, PCB Inspection Microscope, Stencil Printer, Pick-and-Place Machine
See the Build tab for the full step-by-step assembly guide.
Generated by YuanQi AI Design System · Query: I want to design a smart wristband that can monitor my heart rate, track sleep and motion with Bluetooth.