STLINK-V3MODS Edge Connector Pin 30

[sammissh]

Hi, there

I'm trying to integrate the STLINK-V3MODS with my STM32H745 based project.

The STM32H745 MCU is powered by an external 3V3 output regulator.

The STLINK-V3MODS board has the following edge pin:

Which is described in the manual as an "Input for STLINK-V3MODS". Now, I'd like to know if I should tie this pin to my 3V3 board voltage, for the MODS to function correctly. Or, if I can just leave this pin floating.

The only functionality I need from the MODS board is to 1. Debug the H745 MCU; 2. Carry serial data via the UART line.
I know that the MODS board powers via USB, hence why I'm a bit confused about this pin 30.

Thank You!

[Tesla DeLorean]

The T_VCC or Target Voltage, isn't to power the MODS board, or the Target, it would be there to power interface buffers to the Target at the correct voltage, in cases presumably where it's not 3.3V.

That the MODS is USB powered is irrelevant.

Check what STM32 Cube Programmer reports as the Target Voltage, it should match what the Target is running at, as provided via T_VCC

[TDK]

It should be tied to VCC on your target STM32 chip. You can leave it floating and still program, but then the programmer won't be able to detect the target voltage, which is a useful feature.

This is what allows the "Target voltage: X" in STM32CubeProgrammer.

[Tesla DeLorean]

Please read the documentation, makes life a lot simpler.

https://www.st.com/resource/en/user_manual/um2502-stlinkv3mods-and-stlinkv3mini-debuggerprogrammer-tiny-probes-for-stm32-microcontrollers-stmicroelectronics.pdf

[sammissh]

Thanks for the help, all. 

I did read that portion of the documentation, but still wasn't entirely sure I understood it 100%.