CM4 core clock limited to 64 MHz while CM7 runs at full configured frequency?

[Prathiksha]

I am working on the NUCLEO-H755ZI-Q, which contains a dual-core STM32H755 (Cortex-M7 + Cortex-M4).

I configure the system clocks in CubeMX as follows:

• SPI1/2/3 Clock MUX: 400 MHz
• System Clock: Configured for high-speed operation
• CM7 core frequency: Correctly matches the configured value (e.g., 200 MHz / 400 MHz depending on settings)

However, when I debug or read the CM4 core clock, I always see:

• CM4 clock = 64 MHz
• It does NOT increase even when I configure higher values in CubeMX. 

Regards,

Prathiksha

[AScha.3]

How you "see" the 64Mhz ?

[TDK]

It's probably an issue with how you're running the program. If the CM7 core is doing the clock configuration, it needs to do that before the clock will be updated. Just running the CM4 side will use the default clock (64 MHz).