STM32U5 RDP2 password accepted but ST-Link fails: DEV_TARGET_NOT_HALTED

[Gaurangthaker]

Hello ST Community,

I am working with an STM32U5 based board and facing serious issue related to RDP Level 2 and debug access. I am attempting to recover the device using STM32 Programmer CLI and Cube Programmer  but it is not responding as expected even after a successful RDP2 password unlock.

$ STM32_Programmer_CLI.exe -c port=swd mode=UR -unlockrdp2 0x18BBDDEF 0x19CCBBEF
-------------------------------------------------------------------
STM32CubeProgrammer v2.19.0
-------------------------------------------------------------------

ST-LINK SN : 003200253133510636303739
ST-LINK FW : V3J15M7B5S1
Board : STLINK-V3SET
Voltage : 3.54V
Error: Unable to get core ID
Error: No STM32 target found! If your product embeds Debug Authentication, please perform a discovery using Debug Authentication
Error: Unable to get core ID

ST-LINK SN : 003200253133510636303739
ST-LINK FW : V3J15M7B5S1
Board : STLINK-V3SET
Voltage : 3.54V

Unlock RDP2 password successfully done
Error: ST-LINK error (DEV_TARGET_NOT_HALTED)

I need help with:
1. why is the core still inaccessible even after RDP2 unlock?
2. Is the device stuck due to TrustZone configuration or another misconfiguration?
3. Solution on above configuration

[Bubbles]

Hello @Gaurangthaker,

did you follow the How to regress from RDP level 2 to RDP level 0 on ... - STMicroelectronics Community exactly, or what were your steps?

also check the discussion under the article, there may be some answer.

BR,

J

[Gaurangthaker]

Hi,
Thanks for the reply 
Yes, we have followed the link:
https://www.st.com/resource/en/application_note/an5347-arm-trustzone-features-for-stm32l5-and-stm32u5-series-stmicroelectronics.pdf

we did as per the steps are mentioned, but still we are not able to proceed and find the proper solution for it.

[Gaurangthaker]

Hi

I have two questions:
1. Does the STM32U5 microcontroller support reversible RDP Level 2?

2. I have attached the steps we followed - it appears that RDP Level 2 is being unlocked, but afterward we are encountering a DEV_TARGET_NOT_HALTED.

Could someone please review the steps and helps us resolve the issue?

[Bubbles]

Hi @Gaurangthaker ,

the error message say that the debug interface cannot connect to the CPU because it's not halted (running). Did you try reseting or power cycling the u5 after unlocking?

Br,

J

[Bubbles]

I also find it strange that your screenshot is not consistent with the 2.19 and it's not showing that the OEM lock is active. Did you establish the connection to the device prior to unlock attempt?

[Bubbles]

I tested the whole process and it works fine, you just need to cold boot the MCU after unlocking to force OBL.