STM32U031K8U6 Download fail.

박인구 · ‎2025-06-23

hi~!

I made a IOT prototype with STM32U031K8T6, but I can't download firmware.

The connection isn't working ad it should, can anyone tell me the issues with the attacked circuit ??

I've tried both j-link and st-link download tools.

please reply from users who have used STM32U031.

Andrew Neil · ‎2025-06-23

Welcome to the forum.

@박인구 wrote:
I can't download firmware.

Please give more details - see: How to write your question to maximize your chances to find a solution

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

TDK · ‎2025-06-23

The schematic looks okay.

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Peter BENSCH · ‎2025-06-23

...except for the repeatedly inserted R7 (NRESET pull-up), which is not necessary for any STM32 because a pull-up is available internally.

However, R7 is only unnecessary and not the cause of unsuccessful downloads. As @Andrew Neil already mentioned, more information is required for this, e.g. photos of the ST-LINK used, in the case of the ST-LINK/V2 also of the back.

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Hl_st · ‎2025-06-23

Hello,

did you have set BOOT0 pin to HIGH before you were trying to download the firmware to MCU?

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박인구 · ‎2025-06-23

Thank you for your answer. As you can see in the circuit diagram, boot0 is fixed to low.

박인구 · ‎2025-06-23

Thank you for your answer. I will attach the image of the ST-Link soon.

Peter BENSCH · ‎2025-06-24

~~You accepted my statement as a solution.~~

How did you get it working?

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csocom · ‎2025-09-25

Edit by ST Moderator: This post has been translated from Korean to comply with the ST Community Terms and Conditions (§10.2).

Seoul, 25 September 2025 The STM32U031K8U6 will not connect to the ST-Link SWD. Downloading is not possible.

I do not know the reason.

Have you managed to resolve this?

Debugging pins: 3.3V, SWDIO, SWCLK, NRESET, GND

NRSET is not used.

Peter BENSCH · ‎2025-09-25

@csocom

The same request applies to your question: more information is required for this, e.g. photos of the ST-LINK used, in the case of the ST-LINK/V2 also of the back.

Regards
/Peter

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