STM32H745IIK6 - "Failed to read ROM table via AP 3" error during debug connection

[KemalUzgoren]

Hello,

We have designed a custom PCB using the STM32H745IIK6 MCU. When we try to connect with STM32CubeIDE using ST-LINK, we get the following error:

Failed to read ROM table via AP 3 
Error in initializing ST-LINK device. 
Reason: Unknown. Please check power and cabling to target.

In our design, we did not use the SMPS configuration — instead, the MCU is powered in LDO mode. The VCAP pins are connected according to the LDO configuration, and the MCU supply voltage (VDD, VDDA) is at 3.3 V.

Could this issue be related to using the LDO power configuration instead of SMPS? Or are there any specific points we should check.

Any guidance on how to properly verify the power configuration and debug connection would be greatly appreciated.

Best regards,

Kemal

[Andrew Neil]

As it's a custom board, you'll need to post your schematics - see: How to write your question to maximize your chances to find a solution.

Has this board ever worked, or is this the first attempt to connect?

See also:

How to solve connection errors when connecting and programming the STM32 target board.

How to solve debugger connection issues.