C8051F52x-53x
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
command, 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.
Accessing Flash from user firmware executing from an unlocked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Locked pages cannot be read, written, or erased. An erase attempt on the page containing the
Lock Byte will result in a Flash Error device reset.
3. The page containing the Lock Byte cannot be erased. It may be read or written only if it is
unlocked. An erase attempt on the page containing the Lock Byte will result in a Flash Error
device reset.
4. Reading the contents of the Lock Byte is always permitted.
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) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a Flash Error device reset.
Accessing Flash from user firmware executing from a locked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Any locked page except the page containing the Lock Byte may be read, written, or erased. An
erase attempt on the page containing the Lock Byte will result in a Flash Error device reset.
3. The page containing the Lock Byte cannot be erased. It may only be read or written. An
erase attempt on the page containing the Lock Byte will result in a Flash Error device reset.
4. Reading the contents of the Lock Byte is always permitted.
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) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a Flash Error device reset.
Rev. 0.3
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SILICON [ SILICON ]
