NUCLEO-G031K8 using external 5V power supply issue

[Gaston]

Hi,

I'm powering my NUCLEO-G031K8 from external 5V (LD2 led is On as expected) but the MCU stays in reset state (Vnrst=1.32V). I've changed the NRST_MODE to 1 (Reset Input only) with no success. The embedded ST-LINK is driving the MCU reset but in this case is not powered (USB disconnected).

How can I fix it?

regards,

gaston

[Antoine Odonne]

Hello Gaston,

No chance to remove this NRST connection from ST-Link thanks to a solder bridge ?

Regards,

Antoine

[Gaston]

Hello Antoine,

No, no chance. I've already checked schematics. I will have to power the board through the USB connector.

gaston

[ValI]

Hey Antoine,

I feel that I've just faced the same issue. In this nucleo Board there is no way to disconnect properly µC NRST pin from ST Link. Thus, when I only wanted to supply the µC by the 3.3V port, the ST-link was not supplied (as wanted) and acted as a current sink disabling the NRST pin to reach 3.3V (it was stuck around 1.3V). I had to cut the track manually and everything worked fine.

Best regards,

Valentin

[Mike_ST]

Hello, thank you for the feedback.

I have entered a ticket in our database (#188171),

just in case, a new version of the PCB is made.