When transition from RDP level 1 to RDP level 0, how to avoid a POR ?

[mich35]

Hello,

MCU: STM32L071

During a transition from RDP level 1 to RDP level 0 the MCU stays stalled.

Only a power supply off then on permits to have it running.

Do you have any suggestion?

Best regards

Mich

[Imen.D]

Hello @mich35 

As described in the reference manual RM0377: 

Note: If the read protection is set while the debugger has been active (through SWD) after last POR (power-on reset), apply a POR (power-on reset) or wakeup from Standby mode instead of a system reset (the option bytes loading is not sufficient).

Try reload the option bytes after programming, for that you can refer to the "3.8.3 Reloading Option bytes by software"section in the reference manual RM0377.

[mich35]

Hello Imen,

I was not with the debugger.

I try to put the system in Standby mode but it does not work, the MCU is stalled. (it works fine from level 0 to level 1)

I follow "STM32 Security tips - 3 RDP without POR" video (level 0 to level 1) but there is nothing for level 1 to level 0.

Best regards

Michel