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December 10, 2025
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NUCLEO-C092RC (MB2046B): UART-based bootloading

  • December 10, 2025
  • 1 reply
  • 603 views

Hi,

I have an STM32C092RCT6U development board and I am trying to perform UART-based bootloading. My board has a B3 button for selecting the boot mode. I am using the Flash Loader Demonstrator to flash the application, but I keep getting the following error:
“No response from the target, the bootloader cannot be started.”

I also tried using STM32CubeProgrammer. I configured it for UART and attempted to connect, but the connection fails with the error:
 “Activating device: KO. Please verify the boot mode configuration and check the serial port configuration. Reset your device and try again.”

I am using a USB-to-UART module connected to PA10 (RX) and PA9 (TX) with the lines crossed (TX→RX, RX→TX).
I also tested using inbuilt Virtual COM port, However, the device is unable to communicate and does not enter the bootloader.

Could you please help me resolve this issue?

Best answer by mƎALLEm

Ok try to disconnect STLINK from the target MCU:

By removing JP4 (UM3353:(

mALLEm_0-1765379473113.png

From the board schematic:

mALLEm_1-1765379543902.png

Removing JP4 disconnects SWCLK from STM32C092. 

And you need to solder the solder bridge SB14 to connect the BOOT0 pin to CN7 connector.

mALLEm_2-1765379677962.png

1 reply

mƎALLEm
Technical Moderator
December 10, 2025

Hello @Nibesh 

Do you mean you are testing with NUCLEO-C092RC board?

Please refer also to this thread.

"To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."
NibeshAuthor
Associate
December 10, 2025

Hi @mƎALLEm ,

In my board only one pin is available for boot (i.e. BOOT0), which is having dual functionality BOOT and SWD_CLK. Even after trying the standard process for boot mode, It failed to detect the device through UART.

mƎALLEm
Technical Moderator
December 10, 2025

Hello,

You still didn't confirm which board are you using: NUCLEO-C092RC board? 

"To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."