STM32U3: RDP Level 1: Flash read access and debugging behavior

[vijayrakesh]

Hello,

I would like clarification on the behaviour of STM32U3 devices when Readout Protection (RDP) Level 1 is enabled.

Configuration:

• TrustZone: Disabled

• Debug interface: SWD/JTAG

Questions:

1. With RDP Level 1, is Flash completely unreadable by any third-party tool or by any boot mode (system memory boot, RAM boot, etc.), except when accessed by application code running on the MCU?

2. With RDP Level 1, is application debugging still supported (attach debugger, halt, step, breakpoints), and are there any known limitations compared to RDP Level 0?

Any confirmation or documentation reference would be appreciated.

Thank you,
Vijay

[TDK · Accepted solution]

1) If you start the chip normally and it boots to user flash, the user program can access flash but the debug interface cannot.

2) STM32CubeIDE won't be able to debug in RDP 1 in my experience. It may be technically possible but the workflow hasn't been set up with that in mind.

Typically development is done in RDP 0 and RDP 1 is set when the program is finished.