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Associate II
Dec 16, 2025 11:33 AM UTC
Question

Programming the board using a USB connection. (at Nucleo-G491RE)

Hello,

First, I would like to express my deepest gratitude for your assistance.

I intend to update the firmware using STM32CubeProgrammer with the following hardware configuration

 

ParkPork_0-1765883915496.png

Additionally, I have set the Boot0 pin to High using a jumper.

However, my PC is not detecting DFU mode.

Additionally, the programmer is not recognizing the USB connection.

ParkPork_1-1765884511107.pngParkPork_2-1765884522001.png

 

Did I miss anything?

 

PS. The board has undergone a full chip erase.

 

6 replies

gbm
Super User
Dec 16, 2025 12:33 PM UTC

You've missed the fact that the pullup is already present in STM32G. No need for an external one. ;)

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice
ParkPorkAuthor
Associate II
Dec 16, 2025 12:36 PM UTC

The same problem occurs even in situations without pull-ups.

I am checking what I might be missing.

gbm
Super User
Dec 16, 2025 12:54 PM UTC

Just noticed that you are powering your board from USB. have you set the power jumpers correctly? What happens if you power it from ST-Link instead?

Also, if you use USB-C connector on the MCU side and C-to-C cable, make sure that 5k1 pulldowns are present on both CC lines.

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice
ParkPorkAuthor
Associate II
Dec 16, 2025 12:58 PM UTC

I hadn't considered using the St-link power supply. I'll double-check this part.

The current connection interface uses a cable similar to the one in the attached photo.

IMG_3679.png

TDK
Dec 16, 2025 1:17 PM UTC

If the ST-link chip on the board is not powered, it can keep the target chip in reset by keeping NRST low.

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ParkPorkAuthor
Associate II
Dec 16, 2025 1:19 PM UTC

The board's 5V LED lights up normally. Even if the LED is lit normally, could the board still not be receiving power?

I'm a beginner developer and there's a lot I don't know. Thank you.