Embedded Flash memory interface
RM0090
94/1731
DocID018909 Rev 11
--
shows how to go from one RDP level to another.
Figure 6. RDP levels
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
Table 17. Access versus read protection level
Memory area
Protection
Level
Debug features, Boot from RAM or
from System memory bootloader
Booting from Flash memory
Read Write Erase Read Write Erase
Main Flash Memory
and Backup SRAM
Level 1
NO
NO
(1)
YES
Level 2
NO
YES
Option Bytes
Level 1
YES
YES
Level 2
NO
NO
OTP
Level 1
NO
NA
YES
NA
Level 2
NO
NA
YES
NA
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.
,EVEL
L
E
V
E
,
L
E
V
E
,
H
!
!
0
$
2
H
#
#
0
$
2
2$0!!H
2$0##H
DEFAULT
/PTIONSWRITE2$0LEVELINCREASE INCLUDES
/PTIONSERASE
.EWOPTIONSPROGRAM
/PTIONSWRITE2$0LEVELDECREASE INCLUDES
-ASSERASE
/PTIONSERASE
.EWOPTIONSPROGRAM
/PTIONSWRITE2$0LEVELIDENTICAL INCLUDES
/PTIONSERASE
.EWOPTIONSPROGRAM
2$0!!H
/THERSOPTIONS MODIFIED
2$0!!H##H
/THERSOPTIONSMODIFIED
7RITEOPTIONS
INCLUDING
2$0!!H
7RITEOPTIONS
INCLUDING
2$0##H
7RITEOPTIONS
INCLUDING
2$0##H
7RITEOPTIONSINCLUDING
2$0##H!!H
AI