Write Protections; Table 11. Access Versus Read Protection Level; Figure 5. Rdp Levels - ST STM32F412 Reference Manual

Embedded Flash memory interface
--
Memory area
Main Flash Memory
Option Bytes
OTP
1. The main Flash memory is only erased when the RDP changes from level 1 to 0. The OTP area remains unchanged.
Figure 5
Options write (RDP level increase) includes
Options write (RDP level decrease) includes
3.6.4

Write protections

Up to 12 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 registers is low, the corresponding sector cannot be
erased or programmed. Consequently, a mass erase cannot be performed if one of the
sectors is write-protected.
70/1163

Table 11. 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.
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
Write Erase
(1)
NO NO
NO
YES
NO
NO NA
NO NA

Figure 5. RDP levels

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
RM0402 Rev 6
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
RM0402
Erase
NA
NA
including
ai16045