STM32WB55 AES2 bus faults when bonded over BLE

[Tyler_gajewski]

We are working on a product on the STM32WB55 that is hard faulting when trying to modify AES2 peripheral registers while actively bonded to a Windows PC over BLE.

What we discovered is that we can use AES2 to encrypt and decrypt just fine, but the moment I bond to a Windows PC and attempt the same encryption/descryption we bus fault, the bus fault is trying to write a 0 to the control register 0x58001800.  My assumption is that when the CPU2 is bonded with the Windows PC it blocks access to the AES2 registers from CPU1 as a security measure.  I cannot find confirmation of this in any of the reference documentations.

I confirmed that when I remove the bond on the Windows PC then perform the encryption using AES2 it works, and when I bond with the Windows PC the AES bus faults trying to access the registers.

Does the STM32WB55 CPU2 restrict AES2 peripheral access to CPU1 when the CPU2 establishes a bonded connection over BLE?

[Tyler_gajewski]

Confirmed my own question.  Yes CPU2 restricts access to AES2 when it's bonded.  In the application note it specifically calls out "AES2 is reserved to the CPU2 and must never be used/accessed by the CPU1"