Write Protections; Table 17. Access Versus Read Protection Level; Figure 6. Rdp Levels - STMicroelectronics STM32F405 Reference Manual

Embedded Flash memory interface
--
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 6
3.7.4

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
94/1731

Table 17. Access versus read protection level

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.
DocID018909 Rev 11
Write Erase
(1)
NO NO
NO
YES
NO
NO NA
NO NA

Figure 6. RDP levels

Booting from Flash memory
Read Write
YES
YES
YES
NO
YES
YES
RM0090
Erase
NA
NA