Pcrop; Table 4. Stm32 Series Rdp Protection Extension - STMicroelectronics STM32 Application Note

Breaking and stepping into code
Thus, any attempt to load, or connect to, an application running from Flash crashes.
It is still possible to load, execute and debug an application in SRAM.
Option Bytes management can be done with ST-LINK utility or with an application
running from SRAM.
Going back to RDP Level 0 completely erases the Flash.
•
Level 2: No Debug.
JTAG/SWD connection is killed. There is no way back. In this case, nobody - even
STMicroelectronics - can perform any analysis of defective parts.
•
Level 0.5 is an additional protection level associated with TrustZone(only available in
STM32L5 Serie). RDP 0.5 is available only when TrustZone is enabled. Debug of
secure domain is forbidden, only non-secure domain can be accessed for debug.
Regression from level 0.5 to level 0 triggers a Flash mass erase, as well as backup
registers and all SRAMs.Regression from RDP Level 1 to RDP Level 0.5 leads to a
partial Flash memory erase: only the non-secure part is erased
Note: Refer to AN5421 and AN5347 for more informations about Trustzone development on
STM32L5 Series.
5.3.2

PCROP

Proprietary Code ReadOut Protection is the ability to define secure area in Flash where user
can locate a proprietary code.
This prevents malicious software or debugger from reading sensitive code.
In case an application with third party code in PCROP area needs to be debugged, the
following points must be considered:
•
Step-into PCROP function is tolerated but ignored (Step-over)
• Access to protected memory through debugger trigs Flash Interruption (Instrument
NMIHandler) and return default pattern for the whole area
For further details refer to section Memory Protection in the reference manual of the device.
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Table 4. STM32 Series RDP protection extension

Product
F0
F2
F3
F4
L0
L1
L4
L5
F7
H7
RDP protection extension
+ backup registers
+ backup SRAM
+ backup registers
+ backup SRAM
+ EEPROM
+ EEPROM
+ backup registers
+ SRAM2
RDP 4 levels
+ backup registers + SRAM2
+ backup SRAM
+ backup SRAM
AN4989 Rev 3
AN4989