Two kinds of nRF52840 dongles, two ways to flash. Not sure? If plugging it in while double-tapping a reset shows up as a USB drive, it's drag-and-drop (Option 1).
Option 1 · Drag-and-drop a .uf2
For Seeed XIAO nRF52840, Makerdiary MDK, and other Adafruit-bootloader dongles. Can't really go wrong — it's just copying a file.
Enter bootloaderPlug the dongle in and double-tap the RESET button. A USB drive appears (e.g. XIAO-SENSE / NRF52BOOT).
3
Drag it onCopy hid-hop-xiao.uf2 onto that drive. The dongle flashes, reboots automatically, and comes up as a USB HID device. Done.
Option 2 · Flash in the browser
For the Raytac MDBT50Q-CX-40 dongle (Nordic Open DFU bootloader) — flashed over Web Serial.
Checking browser compatibility…
1
Enter DFU modeUnplug the dongle. Hold the button and plug it back in while holding. Release after ~1 second.
2
Connect & flashClick below and pick the dongle's serial port (often Open DFU Bootloader or an nRF port).
Idle.
Shoutouts & thanks ♥
This flasher exists because of the folks in our
issues:
@drhaitch —
for asking the obvious-in-hindsight question: "can I just get a compiled firmware and drop it on the dongle?"
You were right to ask. This page is the answer. 🙌
@jacobmarciniec —
for jumping in to help a stranger compile it, README-in-hand, and being lovely about it.
That kindness is the whole vibe. 🤝
Thank you both. Open hardware is better with people like you in the threads.