STM32F103 UART Bootlader: "Error activating device: KO"

gadi · ‎2025-12-08

Hello,

I'm new to this STM32 products. We designed custom module with STM32F103CBT6TR. We are facing issue with serial boot loader.

I'm using CH340 UART to USB converter module.

CH340 MOD TX --> Our Module's RX

CH340 MOD RX --> Our Module's TX

CH340 MOD GND --> Our Module's GND

And our module is powered by USB connector.

Boot mode configuration

Boot 0 is HIGH

Boot 1 is LOW

I'm using STM32cube programmer tool.

When I try to connect our module, I'm seeing the above error.

Just to confirm CH340 module, I tried that with Nucleo board. With Nucleo board I can see it is able to connect without throwing any error.

I tried other reccomondations which are mentioned in this community post like hold reset button and plug USB and then try pressing connect in the STM32cube programmer. But that also, didn't help.

Any help will be really appreciated.

Thank you.

mƎALLEm · ‎2025-12-08

Hello @gadi and welcome to the ST community,

According to your description, the issue is more likely linked to your custom board.

You need to post your schematics.

+ Check you hardware, and your wiring. It could be also a bad soldering.

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.

gadi · ‎2025-12-08

Hello, here is my schematics.
F1_STEERING_MODULE_SCH.pdf

Since our device can be powered not only by USB, in one of your document, it is mentioned we should use PA9 of VBUS sense(USB VBUS). This resulting in using PB6 and PB7 as UART. But we had a connection for PA9 and PA 10 to some header, we are using that header pins for UART line. We checked voltage levels of Boot lines that is as expected as it is supposed to be and also we checked continuity of the tx, rx lines which are proper only. We got assembled our components from JLCPCB. We checked two boards. All two boards throwing same issue.