Write Protections; Table 13. Access Versus Read Protection Level; Figure 5. Rdp Levels - ST STM32F40 Series Reference Manual

Embedded Flash memory interface
Table 13. Access versus read protection level
Memory area
Main Flash Memory
and Backup SRAM
Option Bytes
OTP
1. The main Flash memory and backup SRAM are only erased when the RDP changes from level 1 to 0. The OTP area
remains unchanged.
Figure 5
Figure 5.
Options write (RDP level increase) includes
Options write (RDP level decrease) includes
3.6.4

Write protections

Up to 24 user sectors in Flash memory can be protected against unwanted write operations
due to loss of program counter contexts. When the non-write protection nWRPi bit
(0 ≤ i ≤ 11) in the FLASH_OPTCR or FLASH_OPTCR1 registers is low, the corresponding
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Debug features, Boot from RAM or
Protection
from System memory bootloader
Level
Read
Level 1
Level 2
Level 1
Level 2
Level 1
Level 2
shows how to go from one RDP level to another.
RDP levels
Write options
including
RDP = CCh
L e v l e
R D P =
- Options erase
- New options program
- Mass erase
- Options erase
- New options program
Doc ID 018909 Rev 4
Write Erase
(1)
NO NO
NO
YES
NO
NO NA
NO NA
RDP /= AAh & /= CCh
Others options modified
Level 1
RDP /= AAh
RDP /= CCh
default
Write optionsincluding
RDP /= CCh & /= AAh
2
C C h
Write options
including
RDP = CCh
Booting from Flash memory
Read Write
YES
YES
YES
NO
YES
YES
Write options
RDP = AAh
L e v l e 0
R D P = A A h
RDP = AAh
Others option(s) modified
Options write (RDP level identical) includes
- Options erase
- New options program
RM0090
Erase
NA
NA
including
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