GeeekPi nRF52840 Micro Dev Kit USB Dongle

Works, no problems.

Managed to get working as a open thread border router with home assistant. You do need to be a tinkerer to be able to get this working. It's not as easy as plugging it in and it works you need to know how serial ports work and some understanding of linux/command line with the os of your choice and I found it easier to use a Linux machine to install and program the device. I could not get this working with the nordic connect programmer tool but I was able to flash it manually after loading a newer bootloader onto the device. The git hub repository is essential for figuring out how to get this working.

A bit mystified when it first turned up, but getting the hang of it now. It's shipped with the UF2 bootloader which makes it really easy to update the firmware simply by copying a .uf2 file onto it but I'd never actually come across this before. However the manufacturer's github site is really helpful nrf52840-mdk-usb-dongle is really helpful and in the firmware/open_bootloader directory there's instructions and a zip file for changing to OpenBootloader so you can use the Nordic nRF Connect programmer to program the thing by dragging and dropping hex files to it. Photo shows the dongle with Thread NCP image flashed attached to a Raspberry Pi acting as OpenThread border router. Debugging is a bit limited obviously but for this component I just wanted something that worked, for the bit I'm interested in I got a Nordic 5340 dev kit with integrated Segger debugger.

Really nicely designed Dongle, and does what it says on the box.

Purchased this item years ago, but just started to use until recently when I need another nrf52840 dongle for a quick rapid prototyping project.Many users have difficulty to download and launch custom firmware with this board (I had this problem too). To resolve it, we would need to delete its own bootloader firmware and reflash the default nRF52840 PCA10059 bootloader firmware to make it work. (Warning: By doing this it would stop the red LED flashing in bootloader mode due to the different pins of the RGB LED GPIO)I have no issue in using the dongle after reflashing the Nordic PCA10059 bootloader firmware, but it is a bit tedious as it need external wirings and J-Link/programmer to achieve this.Not a recommended item to get unless you have J-Link or alternative programmer. Better just get the official nRF52840 dongle instead.