( ARM's ) Serial Wire Debug, bit-bang version, on the cheap bluepill ( stm32f103 ) board
This implement a subset of ARM's swd on a stm32F103, AKA bluepill board.
It's specifically designed to do a mass_erase, ie., clear the protection bits and ALL flash/ram contents for a nrf52832 MCU.
For the normal swd programming, better to use "normal" tools like openocd ou blackmagic probe.
Nordic's nrf52 SDK does provide some way to do this by using a SEGGER J-Link and some compiled binaries. It's useless for "exotic" configurations, like a musl based system or no J-Link debugger.
Or, you can do it with a blue pill, Mecrisp stellaris Forth, some files from Embello and this repo.