When STM32 MCU adopts SWD mode to download programs, swclk and swdio pins of the MCU are occupied, wherein swclk is a synchronous clock signal and swdio is a two-way data signal. For different stm 32 microcontroller, the position of these two pins is different.
In addition to the above two pins, the swd port also needs to be co-located with the MCU. As for whether the MCU target board provides 3.3v power to the swd download tool, it depends on the specific model of the download module.