XIAO nRF52840 Sense Plus Bluetooth 5.4 TinyML Board 64MHz Cortex-M4F 20 I/O 6-Axis IMU PDM Mic NFC 1MB Flash 2MB QSPI

XIAO nRF52840 Sense Plus Bluetooth TinyML Development Board

The XIAO nRF52840 Sense Plus is a compact, low-power wireless microcontroller development board built around the Nordic nRF52840 SoC. It combines a 64MHz Arm Cortex-M4 processor with FPU, Bluetooth Low Energy 5.4, Bluetooth Mesh, NFC, a six-axis IMU and a PDM digital microphone. Expanded castellated pins and rear SMD pads provide additional I/O capacity for TinyML, wearable electronics, wireless sensors and compact board-to-board systems.

Technical Specifications

• Product model: XIAO nRF52840 Sense Plus
• Microcontroller: Nordic nRF52840 SoC
• Processor architecture: 32-bit Arm Cortex-M4 with FPU
• Maximum processor frequency: 64MHz
• Internal Flash memory: 1MB
• RAM: 256KB
• Additional onboard memory: 2MB QSPI Flash
• Wireless connectivity: Bluetooth Low Energy 5.4
• Mesh connectivity: Bluetooth Mesh
• Wireless antenna: Onboard 2.4GHz antenna
• NFC: Supported through exposed multifunctional NFC pins
• Motion sensor: LSM6DS3TR-C six-axis IMU
• IMU functions: Three-axis accelerometer and three-axis gyroscope
• Audio sensor: Onboard PDM digital microphone
• Multifunctional I/O pins: 20
• PWM-capable GPIOs: Up to 18 according to the detailed interface specification
• Analog inputs: 6 ADC channels
• UART interfaces: 2
• I²C interfaces: 1
• SPI interfaces: 2
• I²S interfaces: 1
• Debug interface: SWD
• Standard edge-pad pitch: 2.54mm
• Additional SMD-pad pitch: 1.27mm
• USB connector: USB Type-C
• Onboard control: RESET button
• Onboard indicators: Three-in-one user LED and charging LED
• Battery-charging IC: BQ25101
• Battery support: Compatible rechargeable single-cell lithium battery
• Specified standby consumption: Less than 5μA under suitable test conditions
• Programming compatibility: Arduino, MicroPython and CircuitPython
• TinyML compatibility: Supports compatible TensorFlow Lite for Microcontrollers workflows
• Dimensions: 21 × 17.8mm
• Component layout: Single-sided surface-mount design
• Mounting options: Compatible pin-header installation or SMD board-to-board soldering

Nordic nRF52840 Processing

The Nordic nRF52840 integrates a 32-bit Arm Cortex-M4 processor operating at up to 64MHz. Its floating-point unit, 1MB internal Flash and 256KB RAM provide resources for Bluetooth protocol stacks, motion and audio processing, embedded control and compact machine-learning models.

Six-Axis Motion Sensor

The onboard LSM6DS3TR-C IMU combines a three-axis accelerometer and three-axis gyroscope. It supports gesture recognition, activity tracking, equipment movement detection, wearable controllers and TinyML motion-classification applications.

PDM Digital Microphone

The integrated PDM microphone captures digital audio without requiring an external microphone module. It is suitable for sound detection, voice-triggered controls, audio classification and other embedded machine-learning experiments.

Expanded I/O and SMD Connectivity

The Plus design increases the number of multifunctional pins to 20 through redesigned castellated edges and additional 1.27mm-pitch rear pads. Two UART interfaces, two SPI interfaces, I²C, I²S, ADC and SWD connections provide flexible integration with sensors, displays, actuators and communication modules.

Bluetooth LE, Bluetooth Mesh and NFC

Bluetooth Low Energy 5.4 and the onboard antenna support communication with smartphones, gateways and compatible peripherals. Bluetooth Mesh enables distributed sensor and automation networks, while exposed NFC pins support compatible external NFC antenna circuits for identification and device commissioning.

TinyML Development

The Cortex-M4F processor, onboard motion sensor and digital microphone provide a compact platform for compatible TensorFlow Lite for Microcontrollers workflows. Developers can collect motion or audio data, train suitable compact models and deploy inference applications for gesture, activity or sound classification.

Low-Power Battery Operation

The board accepts power through USB Type-C and supports operation with a compatible rechargeable single-cell lithium battery. Integrated BQ25101 charging management and specified standby consumption below 5μA under suitable conditions support wearable and intermittently active wireless devices.

Typical Applications

• TinyML motion and audio classification
• Gesture-recognition devices
• Voice-activated embedded controls
• Wearable electronics and activity trackers
• Bluetooth Low Energy sensors
• Bluetooth Mesh networks
• NFC-enabled embedded devices
• Battery-powered AIoT nodes
• Robotics and equipment monitoring
• SMD board-to-board embedded systems