Skip to main content
AStre
Associate III
November 14, 2025
Question

STM32CubeProgrammer connection to MCU that has read-out protection

  • November 14, 2025
  • 3 replies
  • 313 views

Hello,

I try to connect the STM32CubeProgrammer (v2.20.0) to the STM32L496 that has enabled Read-Out Protection, but it is not possible. I need just to do the full chip erase and download new firmware.

I remember that STM32CubeProgrammer (v2.0.0) allowed to erase the whole ship and connect to MCU successfully. Unfortunately, this old version doesn't work on Windows 11.

Please help me to execute these two steps (full chip erase and connect) for the STM32L496 that has Read-Out Protection enabled.

Thanks,

Alex

3 replies

Technical Moderator
November 16, 2025

Hello @AStre 

Did you try "Connect Under Reset" mode? Then, perform a "Full Chip Erase".

"When your question is answered, please close this topic by clicking ""Accept as Solution"".ThanksImen"
AStre
AStreAuthor
Associate III
November 17, 2025

Hi Imen.D,

I tried to use "Connect Under Reset" mode using UART connection, but got the following message:

"Device is under Read Out Protection or target is held under reset!
If you want to disable RDP please reconnect with Read Unprotect enabled."

I still can't connect to the Read Out Protected MCU STM32L496 populated on my board. I can connect and program blank chip or chip without Read Out Protection.

Thanks,

Alex

 

 

MM..1
Chief III
December 5, 2025

using UART with under reset is unreal tournament...

Clean way is use ST-Link for this and for example command line CLI with switch -rdu remove this for you.

 

AStre
AStreAuthor
Associate III
November 21, 2025

Even the new recently released version 2.21.0 doesn't allow to connect to MCU that has Read-Out Protection. The old version 2.0.0 allows to execute two step connection (full erase and connect) in this case.

Can anybody else help to solve this problem? It is not solved yet for version 2.21.0.

 

Technical Moderator
December 5, 2025

Hi @AStre 

Try powering the MCU: Off then On, connecting via STM32CubeProgrammer, setting RDP to 0xBB, then resetting RDP to 0xAA and retrying the chip erase. Wait a few seconds for the option bytes to be restored (check all sectors in Option Bytes). Then disconnect and reconnect the device to STM32CubeProgrammer. Hope this helps!

Did you try the CLI to disable RDP? The UM2237 will help you on page 118.

Please share the log file or screenshot if this issue is not resolved.

"When your question is answered, please close this topic by clicking ""Accept as Solution"".ThanksImen"