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Power-on startup Referenca Manual vs Cube-MX

Associate III


according to RM0433 6.4.1 "System supply startup" at point 5.

"The software shall then initialize the system including supply configuration
programming in PWR control register 3 (PWR_CR3). Once the supply configuration
has been configured, the ACTVOSRDY bit in PWR control status register 1
(PWR_CSR1) shall be checked to guarantee valid voltage levels"

How should I understand it? Should the software always wait for ACTVOSRDY bit or should it only if PWR_CR3 is modified?

Early start-up in Reset_Handler routine delivered by Cube-MX in /Startup/startup_stm32h7xx.s writes already to SRAM without checking the ACTVOSRDY bit.

Quite late initialization in Cube-MX inside SystemClock_Config() does wait for ACTVOSRDY bit with help of:


but there are no writes to PWR_CSR1 at this place. Moreover, two lines befere there is SRAM access what should not work if exactly ACTVOSRDY is not set as stated in RM0433 in
"As long as ACTVOSRDY indicates that voltage levels are invalid, the system is in
Run* mode, write accesses to the RAMs are not permitted and VOS shall not be

Who is wrong, Cube-MX or Reference manual?