STLINK-V3MODS Information

[CChic.1]

I am trying to use the STLINK-V3MODS debugger on my system. I need information about the device but can't seem to find much. I have the following specific questions:

1. What is GNDDET (Pin 5 of the "32-pin edge connector")? There is no description of this in the publicly released ST documents. Search of the internet says it is a ground detection pin but sources disagree as to whether it is for the STLINK to detect GND of the target or for the target to detect GND of the STLINK. I need to know if it should be connected on my board, but would also like to know its intended purpose.

2. What is T_VCC (Pin 30 of the "32-pin edge connector")? I've seen on the forums that it can be connected to my VCC so the STLINK can sense the voltage of my VCC but again, nothing in the official ST documentation.

3. I am planning on using the GPIOs to control a master power down signal for my entire system. The signal is pulled to +5V through a 10k resistor, pulling it to GND will put the entire system in reset. What is the state of this pin when the device is initially powered on? Is the pin 5V tolerant or do I need to put a FET in series?

4. The primary use of this device is to allow in circuit flashing of my MCU over SWD. I've connected the GNDs between the STLINK and my MCU GND, SWDIO, SWCLK and the T_NRST to my MCU. Is there anything else that needs to be connected in order to facilitate flashing of code?

If at all possible, please provide links to ST documentation to backup your answers. I'd like to have official documentation to guide my decisions before designing this into a large and expensive PCB.

[TDK]

1. What is GNDDET (Pin 5 of the "32-pin edge connector")? There is no description of this in the publicly released ST documents. Search of the internet says it is a ground detection pin but sources disagree as to whether it is for the STLINK to detect GND of the target or for the target to detect GND of the STLINK. I need to know if it should be connected on my board, but would also like to know its intended purpose.

It's an output from STLINK, so it is for you board to be able to detect the debugger. Pin will be tied to GND with debugger attached.

um2502-stlinkv3mods-and-stlinkv3mini-debuggerprogrammer-tiny-probes-for-stm32-microcontrollers-stmicroelectronics.pdf

2. What is T_VCC (Pin 30 of the "32-pin edge connector")? I've seen on the forums that it can be connected to my VCC so the STLINK can sense the voltage of my VCC but again, nothing in the official ST documentation.

It's an input. It allows STLINK to sense the voltage on your chip. You should connect it.

um2502-stlinkv3mods-and-stlinkv3mini-debuggerprogrammer-tiny-probes-for-stm32-microcontrollers-stmicroelectronics.pdf

4. The primary use of this device is to allow in circuit flashing of my MCU over SWD. I've connected the GNDs between the STLINK and my MCU GND, SWDIO, SWCLK and the T_NRST to my MCU. Is there anything else that needs to be connected in order to facilitate flashing of code?

Required, no, but T_VCC can be helpful in order to assess the voltage on the board.

um2502-stlinkv3mods-and-stlinkv3mini-debuggerprogrammer-tiny-probes-for-stm32-microcontrollers-stmicroelectronics.pdf

[CChic.1]

I greatly appreciate the feedback. Is there any place in the linked manual that talks about the GNDDET and T_VCC pins? I can only find GNDDET in two places: page 17 describing the pinout for the 32-pin edge connector (I do see it listed as an output) and page 19 describing CN5 pinout.

Similarly, T_VCC appears on Page 18 (32-pin edge connector pinout) with a note stating it is an input for the STLINK and page 19 (CN5 pinout) again with a note that it is a pinout.

I am guessing by now that this information has been removed from the latest version of this manual. Is there a repository of previous versions somewhere?

Thanks,

Charles

[TDK · Accepted solution]

That's all I can find for this board.

There are probably older versions floating around Google. No official "old version" repo is available. I doubt the older versions have more information--usually manuals are expanded in new revisions, not redacted.

You can read about T_VCC on other ST-link user manuals. It serves the same function here.

Probably GND_Detect is on other programmers as well. Yes, here is both of them in a little more detail.