Is it possible to use the STLINK V3 CN1 without T_VCC?

[JAnto.4]

HI!

I'm working on a design where I need to minimize the number of pins given space problems. I plan to use an ST-LINK/V3 SET without the expansion board, so I'll use just the MB1441 one.

I can't find the official MB1441 board schematic to discover this myself; that's why I'm bothering you.

I will use SWD from MB1441 CN1 with GND, CLK, DIO, NRST, and SWO and want to avoid the T_VCC. I would like to know if this is possible. My target board is 3.3V.

BTW, I'm using STMCubeIDE, and the target is an STM32F207 chip.

Thanks in advance, Julian

[AScha.3]

i just can say: i tried STlink V3 mods , connect just gnd/sdw/swc/swo (+software reset) ; working normal, just see "0,0V on target" , but you could connect this to any 3v3 on the V3 itself , to keep "3,3V on target" message.

[Pavel A.]

I've just recently hit the same thing with ST-LINK v3 minie. It refuses to work without target VCC connected. Can't find an option in the tools to ignore the T_VCC.

[JAnto.4]

I guess it is given by the level-shifting circuitry which is not properly biased without T_VCC. I hoped it worked with 3.3V in the absence of T_VCC.

I will try to capture the schematic on Friday after receiving the STLINK V3.

Thanks for your help.

[LucaP]

@JAnto.4, have you been able to verify if T_VCC can be left unconnected?
Thanks! 

[Tesla DeLorean]

Honestly how hard is this to actually try yourself?

It doesn't even have to come from the target itself, it just needs to be wired to a voltage appropriate for the target.

You will need a ground connection. 

The debug signals can be exposed in many ways, as castellations on the edge, or on a break-off tab beyond the final board but on the panel.

[LucaP]

I am not saying that it is hard per se, but since I have read about different people have different outcomes with the T-VCC and the OP seem to have the exact same setup/tools/needs that I have, I though that hearing his/her experience could be useful before I proceed with my own (uneasy) testing. Anyhow, thanks for your feedback