Booting from the Main Flash Memory on the STM32L4

ikaz · ‎2026-04-26

The STM32L476 does not have an nBOOT0 option bit in its option bytes. Is there a way to boot from the main flash memory without using the BOOT0 pin?

KDJEM.1 · ‎2026-04-27

Hello @ikaz and welcome to the community;

According to the reference manual, the main flash is selected as boot area when BOOT0 is 0.

Please look at table 4 in RM0351:

Thank you.

Kaouthar

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View solution in original post

KDJEM.1 · ‎2026-04-27

Hello @ikaz and welcome to the community;

According to the reference manual, the main flash is selected as boot area when BOOT0 is 0.

Please look at table 4 in RM0351:

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.

Andrew Neil · ‎2026-04-27

@ikaz wrote:
Is there a way to boot from the main flash memory without using the BOOT0 pin?

What do you mean by that?

On this chip, BOOT0 is a dedicated pin with no alternate functions; it is never unavailable - so what's the reason behind not wanting to use it ?

Note that you can enter the system bootloader from application code:

How to jump to system bootloader from application code on STM32 microcontrollers

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.

ikaz · ‎2026-04-27

Thank you for your reply.
My question was about what to do if, due to some error, the BOOT0 pin on the board hasn’t been properly configured.
It seems there’s nothing that can be done about the L476 after all. Thank you.