STM32F429I-DISC1 Auto Reset, Debugger Disconnect

BlueB_Ashutosh · ‎2026-05-26

Hi everyone,

I am facing an issue with my STM32F429I-DISC1 board.

The board automatically resets after around 20–30 seconds and continuous debugging is not possible because debugger disconnects. STM32CubeProgrammer also cannot maintain stable connection for long time.

I tried flashing different simple codes (including LED blink), but same behavior is observed.

I also tried powering the board using external 5V and GND. In that condition, MCU seems to work as expected, but COM LED (LED1 red) continuously blinks and LED2 stays ON.

Can anyone suggest whether this indicates power section issue, ST-Link issue, or MCU damage?

Thanks.

Andrew Neil · ‎2026-05-26

welcome to the forum

Please see How to write your question to maximize your chances to find a solution for best results.

@BlueB_Ashutosh wrote:
The board automatically resets after around 20–30 seconds and continuous debugging is not possible because debugger disconnects. .

How do you know, specifically, that it resets ?

I presume this is when powered via the CN1 ST-Link connector?

Does the USB connection drop?

Have you measured at the STM32 3V supply - is it stable?

Is this a new board, or one that's been previously enjoyed by you and/or others?

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.