Skip to main content
Hammer1
Visitor II
August 25, 2025
Solved

Maximum baud rate USART protocol used in the STM32U5 bootloader

  • August 25, 2025
  • 2 replies
  • 596 views

Akkording to AN3155, July 2025: "The highest tested baud rate (BHigh) is 115200."

Have tried with 921600 and that seems to work fine. 

Is the recommodation from ST that not use above 115200?

This topic has been closed for replies.
Best answer by mƎALLEm

Hello,

The feedback from our internal team:

When the USART used in the bootloader is in auto-baudrate mode, the max baudrate is 921600. But when the USART used is non auto-baudrate, in this case, 115200 is the max recommended.

We plan to clarify that in the documentation.

Does it answer your question?

 

2 replies

mƎALLEm
mƎALLEm
ST Technical Moderator
August 25, 2025

Hello,

I'm checking that internally and get back to you when I have any feedback.

(Internal ticket number 216214)

To give better visibility on the answered topics, please click "Best answer" on the reply which solved your issue or answered your question.
mƎALLEm
mƎALLEmBest answer
ST Technical Moderator
August 25, 2025

Hello,

The feedback from our internal team:

When the USART used in the bootloader is in auto-baudrate mode, the max baudrate is 921600. But when the USART used is non auto-baudrate, in this case, 115200 is the max recommended.

We plan to clarify that in the documentation.

Does it answer your question?

 

To give better visibility on the answered topics, please click "Best answer" on the reply which solved your issue or answered your question.
Terms & ConditionsAccessibility statement