Failed to read ROM table via AP 3 - Failed to start GDB server

Official Hardware Portenta Family Portenta H7
1

I've seen this issue in a few places. Some with solutions, none of which have worked for me. I am programming the Portenta H7 via a Portenta Breakout board with an ST Link v2 using STM32CubeIDE.

UPDATE 05/01/24:

I no longer believe this is a debugger only problem. CM7 is always successful in flashing and debugging or running. The CM4 never gets successfully flashed so the debugger never runs.

CM7 Debug Configuration
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CM4 Debug Configuration
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The ST Link GDB Server cannot flash the CM4 in either debug or Release mode.

The debug configurations are setup the same for each as described in AN5361 Section 3 (see screen shots above).

I can start the CM7 debugger with no problems. When I start the CM4 debugger, I get this error:

COM frequency = 4000 kHz
Target connection mode: Attach Failed to read ROM table via AP 3

Error in initializing ST-LINK device.
Reason: Unknown. Please check power and cabling to target.

With this dialog popup:

Error in final launch sequence:

Failed to start GDB server
Failed to start GDB server
Error in initializing ST-LINK device.
Reason: (255) Unknown. Please check power and cabling to target.

ST Link connections are fine as I can download the Bootloader, CM7 and CM4 .elf files from STMCubeProgrammer.

  • The Bootloader (portentah7_bootloader_mbed_hs_v2.bin)
  • CM7 address 0x08040000
  • CM4 address 0x08100000
  • My linker file for both CM7 and CM4 FLASH entry are set accordingly
  • Debugger configurations for both CM7 and CM4 Startup->Set program counter (hex): are set accordingly

The power mode for CM4, as suggested in this post, is generated correctly with my version of STM32CubeIDE (1.15.1)

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

This post on GitHub follows the same debugger setup as AN5361 Section 3 with one exception: in the CM7 configuration, it shows 'Halt all cores' as checked which contradicts AN5361 . Which one is correct or does it matter? I have also implemented this suggestion from that post:

while(__HAL_RCC_GET_FLAG(RCC_FLAG_D2CKRDY) != RESET) { asm("NOP"); }

Also, these OB settings are checked:

NRST_STOP_D2
NRST_STBY_D2

If more details are needed, please don't hesitate to ask.

Of course, all help/suggestions are greatly appreciated!

2

Using STM32CubeProgrammer, make sure the BCM4 Option Byte (OB -> User Configuration->BCM4) is checked. This enables CM4 Boot.

Credit for this fix goes to @RomainR. from ST Microelectronics. Thank you Romain!