C8051F300 Datasheet, PDF (89/176 Pages) List of Unclassifed Manufacturers – Mixed Signal ISP Flash MCU Family

C8051F300/1/2/3/4/5
Table 10.2. Security Byte Decoding
Bits
Description
7–4
Write Lock: Clearing any of these bits to logic 0 prevents all Flash
memory from being written or page-erased across the C2 interface
3–0
Read/Write Lock: Clearing any of these bits to logic 0 prevents all
Flash memory from being read, written, or page-erased across the
C2 interface.
The lock bits can always be read and cleared to logic 0 regardless of the security settings.
Important note: The only means of removing a lock (write or read/write) once set is to erase the
entire program memory space via a C2 Device Erase command.
C8051F300/1/2/3
Reserved
Lock Byte
0x1E00
0x1DFF
0x1DFE
FLASH memory
organized in 512-byte
pages
0x0000
C8051F304
Reserved
Lock Byte
0x1000
0x0FFF
0x0FFE
FLASH memory
organized in 512-byte
pages
0x0000
C8051F305
Reserved
Lock Byte
FLASH memory
organized in 512-byte
pages
0x0800
0x07FF
0x07FE
0x0000
Figure 10.1. Flash Program Memory Map
The level of Flash security depends on the Flash access method. The three Flash access methods that
can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on
unlocked pages, and user firmware executing on locked pages.
Accessing Flash from the C2 debug interface:
1. Any unlocked page may be read, written, or erased.
2. Locked pages cannot be read, written, or erased.
3. The page containing the Lock Byte may be read, written, or erased if it is unlocked.
4. Reading the contents of the Lock Byte is always permitted only if no pages are locked.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
6. Unlocking Flash pages (changing ‘0’s to ‘1’s in the Lock Byte) requires the C2 Device Erase com-
mand, which erases all Flash pages including the page containing the Lock Byte and the Lock
Byte itself.
7. The Reserved Area cannot be read, written, or erased.
Rev. 2.8
89