NUCLO-H755ZI-Q Unable to debug CM4

[Vero]

Hi community,

I build and program both CM without error and debugger configuration as in the AN5361 .

The Nucleo- runs with maximum frequency  480 MHz, and Power supply:

  HAL_PWREx_ConfigSupply(PWR_SMPS_2V5_SUPPLIES_LDO);

  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);

 I am debugging the CM7 however I'm not able to debug CM4 and have this error :

Starting server with the following options:

STMicroelectronics ST-LINK GDB server. Version 7.5.0

Copyright (c) 2023, STMicroelectronics. All rights reserved.

Starting server with the following options:

Persistent Mode : Disabled

Logging Level : 1

Listen Port Number : 61234

Status Refresh Delay : 15s

Verbose Mode : Disabled

SWD Debug : Enabled

Failed to read ROM table via AP 3

Error in initializing ST-LINK device.

Reason: Unknown. Please check power and cabling to target.

I've already tried with the advice of:

Unable to connect to STM32H7 devices - STMicroelectronics Community

can you help me?

[SofLit]

Hello,

Did you modify your board HW to get SMS/LDO power config?

Also, if the CM4 is using Low power mode the debug will be lost.

Also becareful : @480MHz you need to set VOLTAGE_SCALE0.

[Vero]

Thanks. 

If I would likes to use only the SMS I can modified:

HAL_PWREx_ConfigSupply(PWR_DIRECT_SMPS_SUPPLY)

but I don't see this option for the  NUCLO-H755ZI-Q on the cube menu. can I set it manually?

In this case the hw changes will not be needed... correct?

Where can I check on Cube the low Power mode of M4?

Them i will put the VOLTAGE_SCALE0.

[SofLit]

The NUCLO-H755ZI-Q board is in SMPS configuration.

The power configuration can be set in RCC menu:

Attached an example of .ioc file for this board.

Warning 1: in SMPS mode you cannot exceed a system frequency of 400MHz/VOS1.

You need to set VOLTAGE_SCALE1 in this configuration.

According to the datasheet:

Warning 2: the software power configuration you load to the MCU should reflect the HW power configuration of your board, otherwise the MCU will be temporarily "lost" and you need to recover the chip by a specific manipulation.

[SofLit · Accepted solution]

The power mode is used for synchronization between CM7 and CM4.

These lines in main.c (CM4) are used for low power mode

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

Uncomment these two lines but you will lose the synchronization between the cores. Here, CM7 needs to start before  CM4 to configure the system before to release CM4 and wake it up from stop mode.