Wireless communication is not just an extra feature in many projects; it is a core requirement. Bluetooth Low Energy (BLE) is the gold standard in the maker and IoT world: low power consumption, wide support in smartphones and laptops, and a vast ecosystem of libraries and tools.
The nRF52840 from Nordic Semiconductor is one of the most powerful microcontrollers in this segment. The dongle version — a USB-stick form factor module featuring an integrated antenna — offers the lowest barrier to entry.
What is the nRF52840?
The nRF52840 is a System-on-Chip (SoC) combining an ARM Cortex-M4 processor with a full Bluetooth 5, Thread, and Zigbee radio onto a single chip.
| Specification | Value |
|---|---|
| Processor | ARM Cortex-M4F @ 64 MHz |
| Flash | 1 MB |
| RAM | 256 KB |
| Radio | Bluetooth 5, 802.15.4 (Thread, Zigbee) |
| USB | Native USB 2.0 full speed |
| GPIO | 48 programmable pins |
The dongle: why this form factor?
- Direct USB connection. Program via a USB bootloader, eliminating the need for an external programmer.
- Integrated antenna. Features a built-in PCB antenna; an external antenna connection is available for critical applications.
- Ideal as a BLE sniffer. Nordic provides firmware that turns the dongle into a functional Bluetooth sniffer inside Wireshark.
What do you use the nRF52840 dongle for?
Standalone BLE device
Using Zephyr RTOS or the nRF5 SDK, you can program the dongle as a fully fledged BLE device: a sensor, a HID device (keyboard, mouse), or a custom peripheral.
Wireless sniffer
Flash Nordic's Sniffer firmware and use the dongle as a passive BLE monitor within Wireshark. This is indispensable for debugging complex BLE connections.
Thread/Zigbee coordinator
The 802.15.4 radio also makes the nRF52840 usable as a Thread or Zigbee coordinator combined with a Raspberry Pi — providing the foundation for a Home Assistant integration.
Getting started: the first steps
- Install nRF Connect for Desktop — Nordic's free toolsuite for flashing, BLE analysis, and updates.
- Choose your development environment:
- nRF5 SDK — a mature SDK with extensive BLE libraries, suitable for production-ready designs
- Zephyr RTOS — modular, open source, and increasingly becoming the industry standard
- CircuitPython — for those who want to jump start quickly without deep embedded knowledge
