How to flash STM32F429zi nucleo via UART without ST-Link?

Asha1 · ‎2025-09-25

Hello,

I'm working with STM32F429ZI nucleo board, and I would like to flash my program using UART (USART1 or UART3 via a usb to ttl converter) instead of ST-Link.I understand that STM32 has a built-in bootloader that can be used for flashing via UART, but I'm not sure about the exact steps or tools required.

when I connect the uart with STM32CubeProgrammer an error message come :-

13:58:51:175 : Error occured while sending Init command.
13:58:51:175 : Error: Activating device: KO. Please, verify the boot mode configuration and check the serial port configuration. Reset your device then try again......

settings I did:

1.the boot0 pin connected with 3v3 and boot1(pb2) connected to ground

2.uart3 pins PB10,and pb11 used for tx and rx respectively

Here’s what I’ve tried / what I need help with:

1. How to connect the UART pins correctly for flashing?
2. What BOOT0 and BOOT1 pin settings are needed?
3. What software can I use on the PC side (e.g., STM32CubeProgrammer or any alternatives)?
4. What file format should I use (.hex or .bin)?
5. How to verify if the STM32 is actually in bootloader mode?

Any help or step-by-step guide would be appreciated.

KDJEM.1 · ‎2025-09-25

Hello @Asha1 ;

As mentioned in AN2606, the STM32F42xxx/43xxx bootloader is activated by applying Pattern 5. So, you need to satisfy the below condition.

I recommend you to look at this STM32 boot and startup tips - 2 Embedded bootloader investigations Mooc and get inspired. This video provides a step-by-step guide.

I hope help you.

Thank you.

Kaouthar

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.

View solution in original post

KDJEM.1 · ‎2025-09-25

Hello @Asha1 ;

As mentioned in AN2606, the STM32F42xxx/43xxx bootloader is activated by applying Pattern 5. So, you need to satisfy the below condition.

I recommend you to look at this STM32 boot and startup tips - 2 Embedded bootloader investigations Mooc and get inspired. This video provides a step-by-step guide.

I hope help you.

Thank you.

Kaouthar

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.

KDJEM.1 · ‎2025-10-02

Hello @Asha1 ,

Are these ressources helped you to flash STM32F429zi via UART?

If you need furthermore support, please don't hesitate to update post.

If your issue is solved, please click on "Accept as Solution" on the reply which solved.

Thank you.

Kaouthar

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.

Shirley.Ye · ‎2025-10-03

3. What software can I use on the PC side (e.g., STM32CubeProgrammer or any alternatives)?

STM32CubeProgrammer can be used. choose uart, and connect.

4. What file format should I use (.hex or .bin)?

both .hex or .bin can be used.