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Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
In unprotected state, corresponding (RDP1 == 0xA5 & nRDP1 == 0x5A) && (RDP2!= 0xCC | nRDP2!=
0x33);
The main memory area and option byte block can be read arbitrarily;
The write protection property of each page can be configured for programming and erasing;
L1 level:
The corresponding ~ ((RDP1 == 0xA5 & nRDP1 == 0x5A) && (RDP2!= 0xCC | nRDP2!= 0x33)) | (RDP2
== 0xCC & nRDP2 == 0x33));
Only the read operation of the main storage area from the user code is allowed, that is, when the program
is started from the main flash memory in non debugging mode, the read operation of the main storage area
is allowed;
Pages 0~1 are automatically write-protected
;
Other pages can be programmed by the code executed in the main flash memory (realizing IAP or data
storage and other functions);
All pages are not allowed to write or erase in debug mode or after booting from internal SRAM (except for
mass erase);
All functions of loading code into the built-in SRAM through JTAG/SWD and then execute it are still valid,
or they can be started from the built-in SRAM through JTAG/SWD, which can be used to remove read
protection;
When the read-protected option byte is rewritten to the unprotected L0 level, all the main storage areas will
be automatically erased, and the process is as follows: (Erasing the option byte block will not result in
automatic whole erasing operation, because the result of erasing is 0xFF, which is equivalent to still being
in the protection state of L1 level)
Write the correct key value sequence to unlock the option byte area in FLASH_OPTKEY;
The bus initiates a command to erase the entire option byte area (Page erase);
Bus write 0xA5 to read protection option byte;
Automatically erase all main storage areas internally;
Automatically write 0xA5 to read protection option byte internally;
When the system is reset (such as software reset, etc.), the option byte block (including the new
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