I am powering STM32G4 Nucleo board with 12V VIN to power the system. The Nucleo board goes into USB enumeration mode (red blinking LED LD1). The enumeration fails without connecting the USB. How to bypass this so I can power it via 12V VIN?

[RomainR.]

Hello @ATiwa.4 (Community Member)

Please, can you confirm you're powering NucleoG4 with external 12V on CN6 VIN pin?

Can you confirm you configure also JP5 jumper on 5V_VIN position ?

In this case LD3 (5V_PWR) must be ON. And if USB STLink is not connected no USB enumeration can start.

Now, if you connect USB STLink, after enumeration, you could debug the device normally?

Can you confirm?

Best regards,

Romain,

[PBadu.1]

Hi @RomainR.​ 

What you're describing is possible for Nucleo-G474RE (Or any Nucleo-64). Setting JP5 to 5V_VIN position seems to allow the STM32G chip to continue to run normally without a USB cable connected.

However, there doesn't seem to be an easy way to do the same with Nucleo-G431KB (Nucleo-32). With only 12V connected (without a USB cable), LD1 is blinking red and the STM32G is not running. Is there a way around this with the Nucleo-G431KB?

Appreciate your help

[RomainR.]

Hello @PBadu.1 (Community Member)

For all board a general rule if the main STM32 does not start as indicated to you the root cause comes from the nRST pin which is pulled to the VSS by the onboard STM32 STLink.

Some Nucleo64 and 32 boards are equipped with jumper allowing this nRST signal to be isolated in order to avoid this.

But in the case of a NucleoG431KB (Nucleo32) the STLinkV3 solve this problem.

I just did a test with this board. The onboard STLinkV3 is V3J2M1 firmware version.

By applying a 12V on CN3.1, the STM32G431KB boots and works as expected.

Can you check the STLinkV3 firmware version and upgrade it ?

Best regards,

Romain,

[PBadu.1]

Thanks for getting back quickly.

The STLink version is V3J10M3 -- Not sure if this is newer or older? Is there anywhere V3J2M1 can be downloaded? Currently observing that upon startup, The STM32G431KB doesn't boot up if the USB isn't connected. Upon connecting the USB, it runs as expected.

[RomainR.]

Yes firmware V3J10M3 is is one of the latest version, to upgrade to the very last one, use STM32CubeIDE -> Help -> STLink Upgrade to update to V3J11M3.

I've tested on my NucleoG431KB and the G431 boot and run with V3J10M3 and also V3J11M3 (picture below shows LD4 On, LD2 blinking by firmware and LD1 blinking red slowly because USB is not connected)

Without USB connected, can you check nRST ? Is it high ?

Does LD4 is on when applying 12V on CN3.1 and GND on CN3.2 ?

Regards.

Romain,

[Hanya]

Hello RomainR

I have the same problem while powering STM32G474RE Nucleo board with external power suspply——it all end up with LD1 blinking red and the board won't boot up.  As you suggested, I update the STLink firmware to V3J11M3 and the problem still exists. Without USB connected, I have  check nRST  is high(about 7V as I set the external power with 5V_VIN on). Can you explain how to check nRST when the Nucleo board work correctly?

[RomainR.]

Hello @Hanya 

Did you apply the UM2505 in chapter 6.4 Power supply, table 6 and figure 11 explain how to powering the Nucleo-G474RE with external power supply input from VIN.
https://www.st.com/resource/en/user_manual/um2505-stm32g4-nucleo64-boards-mb1367-stmicroelectronics.pdf

But that said, how can you measure a voltage of 7V on the nRST pin?
nRST pin voltage level must be equal to VDD = 3.3V (thank to U12 LD0 3.3V on board)
Can you describe more precisely how did you do it?

BR

Romain,