STM32H747IIT6 CM4 not responding

aradhyab · ‎2026-02-05

I am working on STM32h747 series. I am debugging both CM4 and CM7. After a while, CM4 stops responding and the debug messages shows:

"Error in final launch sequence:

Failed to start GDB server

Error in initializing ST-LINK device.

Reason: (4) No device found on target."

If I run CM7 independently, it works but CM4 is not responding. I tried to erase the entire board but CM4 is still not responding and the same message is appearing.

mƎALLEm · ‎2026-02-05

Hello @aradhyab and welcome to the ST community,

If you have generated the code based on CubeMx or used one of the HAL examples, CM4 enters into a low power mode state and the debug is a bit tricky.

Do you have this definition in both mains (CM7 and CM4)?

#define DUAL_CORE_BOOT_SYNC_SEQUENCE

If yes undefine it.

Check also if CM4 is disabled in the option byte.

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aradhyab · ‎2026-02-06

Hello @mƎALLEm

Thank you for the prompt response.

Regarding

#define DUAL_CORE_BOOT_SYNC_SEQUENCE

I have undefined it but it still does not work. It shows the same error.

Can you please guide me on how to check if the option byte is enabled or disabled?

mƎALLEm · ‎2026-02-06

@aradhyab wrote:

Regarding
#define DUAL_CORE_BOOT_SYNC_SEQUENCE

Did you undefine it at both sides CM7 and CM4?

@aradhyab wrote:

Can you please guide me on how to check if the option byte is enabled or disabled?

Using the STM32CubeProgrammer:

BCM4 should be checked as shown in the screenshot.

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