XIAO nRF52840 Plus Unsoldered Bluetooth 5.4 Board 64MHz Cortex-M4F 20 I/O 1MB Flash 256KB RAM 2MB QSPI NFC

XIAO nRF52840 Plus Unsoldered Bluetooth Development Board

The XIAO nRF52840 Plus is a compact, low-power wireless microcontroller development board based on the Nordic nRF52840 SoC. It combines a 64MHz Arm Cortex-M4 processor with FPU, Bluetooth Low Energy 5.4, Bluetooth Mesh, NFC, 1MB internal Flash, 256KB RAM and 2MB additional onboard Flash. Expanded castellated pins and rear SMD pads provide increased I/O capacity for wearable electronics, wireless sensors, IoT devices and compact board-to-board systems.

Technical Specifications

• Product model: XIAO nRF52840 Plus
• Version: Unsoldered
• 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 Flash
• Wireless connectivity: Bluetooth Low Energy 5.4
• Mesh connectivity: Bluetooth Mesh
• Wireless antenna: Onboard 2.4GHz antenna
• NFC: Supported through multifunctional NFC pins
• Multifunctional I/O pins: 20
• 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 rear 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 management: Rechargeable lithium-battery charging support
• Specified standby consumption: Less than 5μA under suitable test conditions
• Programming compatibility: Arduino, MicroPython and CircuitPython
• Dimensions: 21 × 17.8mm
• Header configuration: Unsoldered
• Component layout: Single-sided component mounting
• Integrated IMU: No
• Integrated microphone: No

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, sensor processing, embedded control and compact machine-learning applications.

Expanded I/O and SMD Connectivity

The Plus version uses redesigned castellated edges and additional 1.27mm-pitch pads on the rear of the board. Its 20 multifunctional I/O pins provide increased connectivity while preserving the compact XIAO footprint. The unsoldered design supports both conventional pin-header installation and SMD board-to-board assembly.

Bluetooth LE, Bluetooth Mesh and NFC

Bluetooth Low Energy 5.4 and the onboard 2.4GHz antenna support communication with smartphones, gateways and compatible wireless peripherals. Bluetooth Mesh can be used for distributed sensor, lighting and automation networks. Exposed multifunctional NFC pins simplify NFC antenna integration and device commissioning.

Extended Peripheral Interfaces

Two UART interfaces, two SPI interfaces, I²C, I²S, six ADC channels and an SWD debugging interface support integration with sensors, audio components, displays, actuators and communication modules. Selected pins perform multiple functions, so interface availability depends on the configured pin assignments.

Low-Power Battery Design

The integrated BQ25101 charging IC supports operation with a compatible rechargeable lithium battery. Specified standby consumption below 5μA under suitable conditions makes the board suitable for portable sensors, wearables and wireless devices that remain inactive for extended periods.

Compact Unsoldered Construction

The 21 × 17.8mm board is supplied without pre-installed pin headers. Compatible 2.54mm headers can be added for breadboard development, while the castellated edges and rear SMD pads support compact integration into custom carrier boards and production equipment.

Typical Applications

• Bluetooth Low Energy devices
• Bluetooth Mesh sensor networks
• NFC-enabled embedded equipment
• Wearable electronics
• Battery-powered IoT sensors
• Compact wireless controllers
• Embedded machine-learning projects
• Mini Arduino-compatible projects
• SMD board-to-board systems
• Education and rapid prototyping