Enabling RDP when TrustZone is active

[mikel-m]

Hi,

I am conducting tests with the HSM and SFI. I have tried the use case of attempting to install an SFI with an HSM that uses other keys. Obviously, I couldn't do it, but now I cannot connect the microcontroller in "normal" mode. If I connect it in "Hot plug" mode and try to change the RDP, it shows the following message:
Enabling RDP when TrustZone is active!
If no valid secure code booting and calling non-secure code, it may prevent disabling TrustZone And RDP.

And if I click OK, it shows the following message:
Your device may be lost FOREVER

What should I do to fix this error so that I can reconnect the microcontroller to the STM32CubeProgrammer?

Best regards,

[Aziz BRIGUI · Accepted solution]

Hello @mikel-m,

Welcome to ST Community :) !

The message you're seeing is a warning not an error, it is displayed because in many configurations, you can lose your device if you set RDP when TrustZone is active.

What I advise is to check section 9 in AN5347.

Basically, to make sure not to lose your chip, the following conditions should be met: 

- nSWBOOT0 option byte is checked (BOOT0 taken from PH3/BOOT0 pin)
- NSBOOTADD1 option byte is configured to 0x17F200 value at 0x0BF9 0000 address (RSS address).
- BOOT_LOCK option byte is unchecked (boot based on the pad/option bit configuration).

Hope this helps,

Aziz