Table 23. Access Status Versus Protection Level And Execution Modes; Figure 7. Changing The Read Protection (Rdp) Level - ST STM32G4 Series Reference Manual

RM0440
If the bit PCROP_RDP is cleared in the FLASH_PCROP1ER, the full mass erase is
replaced by a partial mass erase that is successive page erases, except for the pages
protected by PCROP. This is done in order to keep the PCROP code. Only when the Flash
memory is erased, options are re-programmed with their previous values. This is also true
for FLASH_PCROPxSR and FLASH_PCROPxER registers (x=1).
Note: Full Mass Erase or Partial Mass Erase is performed only when Level 1 is active and Level 0
requested. When the protection level is increased (0->1, 1->2, 0->2) there is no mass erase.
To validate the protection level change, the option bytes must be reloaded through the
OBL_LAUNCH bit in Flash control register.
Write options Including
Options write (RDP level increase) includes:
Options write (RDP level decrease) includes

Table 23. Access status versus protection level and execution modes

Protection
Area
level
1
Flash main
memory
2
1
System
(2)
memory
2
Embedded Flash memory (FLASH) for category 2 devices

Figure 7. Changing the read protection (RDP) level

RDP = 0xCC
Level 2
RDP = 0xCC
- Options page erase
- New options program
- Full Mass erase or Partial Mass erase to not
erase PCROP pages if PCROP_RDP is cleared
- Backup registers and CCM SRAM erase
- Options page erase
- New options program
User execution (BootFromFlash)
Read Write
Yes
Yes
Yes
Yes
RDP ≠ 0xAA and RDP ≠ 0xCC
Others options modified
Level 1
RDP ≠ 0xAA
RDP ≠ 0xCC
default
Write options including
RDP ≠ 0xCC and RDP ≠ 0xAA
Write options including
RDP = 0xCC
Erase
Yes Yes
Yes Yes
No No
No No
RM0440 Rev 1
Write options including
RDP = 0xAA
Level 0
RDP = 0xAA
RDP = 0xAA
Other(s) option(s) modified
Options write (RDP level identical) includes
- Options page erase
- New options program
Debug/ BootFromRam/
BootFromLoader
Read Write
No No
N/A N/A
Yes No
N/A N/A
MS33468V2
(1)
Erase
(3)
No
N/A
No
N/A
165/2083
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