https://infocenter.nordicsemi.com/topic/struct_sdk/struct/sdk_nrf5_latest.html

https://www.nordicsemi.com/Software-and-tools/Software/nRF5-SDK/Download#infotabs

SDK need to work with SoftDevices, https://github.com/jinlong80/s140nrf52720

https://infocenter.nordicsemi.com/topic/ug_nrf52840_dongle/UG/nrf52840_Dongle/intro.html

The nRF52840 Dongle (PCA10059) is the preferred hardware to be used with the nRF Connect for Desktop software package to develop and test your nRF-based wireless solutions. The hardware supports all the short range wireless standards available on the nRF52 family of devices, and the built-in USB device controller provides a high data throughput communication interface.

The nRF52840 Dongle can also be used together with the nRF5 SDK for product development based on the the nRF52840 SoC.

The nRF52840 Dongle is a low-cost, versatile USB development dongle for Bluetooth® Low Energy, ANT™, 802.15.4, and user-proprietary 2.4 GHz applications using the nRF52840 SoC.

Key features:

nRF52840 flash-based ANT/ANT+™, Bluetooth Low Energy SoC solution Button and LEDs for user interaction 15 GPIO available on a castellated edge Onboard USB bootloader with buttonless support USB support

Before you start, check that you have the required hardware and software.

The nRF52840 Dongle consists of hardware (PCA10059), access to application firmware examples, documentation, hardware schematics, and layout files.

Complete a few steps to set up the hardware and install the required software.

The nRF52840 Dongle can be programmed through the built-in USB bootloader.

The nRF52840 Dongle can be used as a development platform for the nRF52840 SoC. It features user configurable LEDs and a button as well as multiple GPIOs available along the board edges. In addition to radio communication, the nRF5240 SoC can communicate with a computer through USB.

https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads