Boot Issue with CM4 - STM32H745ZIT6

[Pavan-Oggu]

Hello Team,

We have a custom STM32H745 board designed and We are able to get the IC up and running on cube programmer and even set option bytes. 

The board is designed with Nucleo-H745ZI-Q schematics and we have verified everything on hardware end.

When we try to program the board with a basic blink sketch following the guide (https://www.st.com/resource/en/application_note/dm00629855-getting-started-with-projects-based-on-dualcore-stm32h7-microcontrollers-in-stm32cubeide-stmicroelectronics.pdf) 

M7 gets debugged and runs. Once I start with M4 I get error messages and it bricks the controller.

I have been pulling up the BOOT0 pin and performing mass erase and trying things again, still it gets bricked when I try to debug CM4.

[Pavan-Oggu]

We are using LDO mode and I can confirm that. I have attached our schematics for reference.

We have missed pull down resistor on boot0 but I have added it externally on the hardware, Similarly I have also added a pull up resistor for PDR_ON pin.

[SofLit]

Hello,

There is a mismatch between your RCC config i.e. you set an external 8MHz source in Bypass mode:

While in your schematics you have an external clock with 25Mhz / Crystal/Resonator mode:

You need to align the RCC config to fit your HW:

Attached the updated ioc file.

[Pavan-Oggu]

Hello SofLit,

Thank you, CM7 boots up and blink sketch works on the board.
But CM4 remains the same. It doesn't get detected at all. Any idea why?

[SofLit]

Please comment these two lines in the main of CM4:

  HAL_PWREx_ClearPendingEvent();
  HAL_PWREx_EnterSTOPMode(PWR_MAINREGULATOR_ON, PWR_STOPENTRY_WFE, PWR_D2_DOMAIN);

These lines make the CM4 to enter in low power mode while debugging.

For debug, I suggest you to comment these lines but you can keep them while in standalone.