How is it possible to power the Nucleo-144 board with an external NEGATIVE power supply (VDD= 0V, VSS= -3v3)?

[HLabi.1]

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[TDK]

Voltage is relative. As long as VDD - VSS = 3.3V, it will work. However, if you have other things connected to the board that think VDD = GND, you're going to have issues.

Information on powering the board from 3.3V is in the user manual:

https://www.st.com/resource/en/user_manual/dm00244518-stm32-nucleo144-boards-mb1137-stmicroelectronics.pdf

[HLabi.1]

According to Table 7 (page 19) and paragraph "External power supply input: + 3.3 V" (page 23), there are two possibilities:

- ST-LINK PCB is cut

- SB3 and SB111 OFF (ST-LINK not powered)

So my question is: If I cut the ST-LINK/V2-1 PCB from the board, is it possible to use the ST-LINK/V2-1 (removed) to program and debug the same board (I removed from)?

According to Table 5 (page 22) and STM32CubeMX:  

VDD_TARGET --> 3V3

SWCLK   --> PA14 

GND    --> GND

SWDIO   --> PA13

NRST    --> NRST

Is it correct to connect the pins as shown in the picture?

[TDK]

Yes, it is. Note that the programmer and the board will need the same ground. I'm unsure if SWDIO/SWCLK are broken out into pins somewhere, but provided you can get at those somehow, you can program the board.