Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
16
/
631
RDP value 0xA5) will be reloaded into the system, and the read protection will be released;
The following access operations to the flash memory will be prohibited:
Access main flash memory from built-in SRAM start execution code (including using DMA);
Access the main flash memory by JTAG, SWV (serial line observer), SWD (serial line debugging)
and boundary scanning;
L2 level: Except that SRAM boot disabled, debug mode disabled, option byte write/page erase disabled and the
protection level cannot be modified (irreversible), other features are the same as L1 level. The L2 level is realized
by configuring another option byte, RDP2. No matter what the value of RDP1 is, as long as it satisfies
(RDP2==0xCC & nRDP2==0x33), it is L2 level.
Table 2-6 Flash read-write-erase
(1)
permission control table
protect
level
Boot mode
Main Flash
Changing a Protection
Level
Perform user
Access area
JTAG/
SWD
Main Flash
System Memory
SRAM
L0
level
Before 4KB of flash
main memory area
Read-Write-
Erase
Read-Write-
Erase
Read-Write-Erase
Read-Write-
Erase
Change to L1 or L2 is
allowed
After 4KB of flash
main memory area
Read-Write-
Erase
Read-Write-
Erase
Read-Write-Erase
Read-Write-
Erase
Flash main memory
area mass erase
Allow
Allow
Allow
Allow
Flash option byte area
Read-Write-
Erase
Read-Write-
Erase
Read-Write-Erase
Read-Write-
Erase
Flash system memory
area
prohibit
prohibit
Read-Write-Erase
prohibit
SRAM (All)
Read and
write
Read and
write
Read and write
Read and
write
L1
level
Before 4KB of flash
main memory area
Prohibit
Read-only
Read-only
Read-only
L0 or L2 is allowed.
When changed to L0,
the main memory area
is automatically erased.
After 4KB of flash
main memory area
Prohibit
Read-Write-
Erase
Read-Write-Erase
Read-Write-
Erase
Flash main memory
Allow
Allow
Allow
Allow