STLink V3 MINIE won't connect to STM32U0 target; V2 and V3_SET connect OK

[Michal Dudka]

I have the following original debuggers:
Stlink V2
Stlink V3_SET
Stlink V3_MINIE (2 pieces)

I was recently testing a simple board with an STM32U083 (powered by 3.3V) and found that two Stlink V3 MINIE units could connect to the MCU. Meanwhile, both the V2 and V3_SET work without any issues.

I observed that after connecting (SWDIO,SWCLK,VDD,GND) to the powered MCU, both the V2 and V3_SET leave SWDIO at 3.3V (pull-up in the MCU) and SWCLK at 0V (pull-down in the MCU). Whereas the MINIE maintains a 3.3V level on both SWDIO and SWCLK. Out of curiosity, I connected an external 10k pull-down resistor to both SWDIO and SWCLK and observed that SWDIO drops (which is fine), but SWCLK does not, meaning that the Stlink V3 MINIE actively holds SWCLK at 3.3V.

 

Am I doing something wrong, or are both MINIE boards defective?

Best regards,
Michal Dudka

[AScha.3]

Hi,

> found that two Stlink V3 MINIE units could connect to the MCU

- thats normal, right ?

>Am I doing something wrong, or are both MINIE boards defective?

What now: they connect - or not ?

 

 

[Michal Dudka]

Sorry, there's a typo there. I meant to say that Stlink V3 MINIE units could not connect to the MCU.

[AScha.3]

Ok :)  .

What shows CubeProgrammer (actual version !) , when connect a miniE ? (updated firmware ? )

[Andrew Neil]

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@Michal Dudka wrote:

connecting (SWDIO,SWCLK,VDD,GND) to the powered MCU

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What if you include NRST in the connection, and try to connect under reset?

[S C]

Hello,

Concerning the signal behavior, it is explained because the V3MINIE embeds level shifters without output enable signal. So outputs (including SWCLK) are always driven. This remark applies also to T_JTDI and T_VCP_Rx. SWDIO can be released because it is bidir and thus can be configured as input for the ST-Link (so not driven by the level shifter).

One point following this difference with V2 and V3SET, is that T_VCC (input for V3MINIE on pin3) is absolutely mandatory for the V3MINIE to work. I don't know if this can explain the issue with CubeProg (because I see 3,02V in the log windows and 0V in the GUI at the right), but I would say this should be the first signal to check in case of connection issue with V3MINIE vs V2 and V3SET (other signals should also be checked, because I guess that connectors differences lead to manual wiring with possible erratic contact)

[Michal Dudka]

The MCU is, of course, powered, and VCC is connected to MINIE. Just to be sure, I also measured the voltage at MINIE and verified that there is 3V coming from the MCU.

Connecting it "under reset"—whether via hardware or software reset—has no effect on this, and the result is the same.

 

I didn’t want you to spend too much time on this; I was just curious if any of you had encountered this issue and had a ready-made solution. Of course, I’ll resolve it by simply not using the MINIE in this case.

Best regards, Michal Dudka