C8051F52X_12 Datasheet, PDF (118/221 Pages) Silicon Laboratories – 8/4/2 kB ISP Flash MCU Family

C8051F52x/F53x
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. Table 12.1 summarizes the Flash security
features of the ’F52x/’F52xA/’F53x/’F53xA devices.
Table 12.1. Flash Security Summary
Action
C2 Debug
Interface
User Firmware executing from:
an unlocked page a locked page
Read, Write or Erase unlocked pages
(except page with Lock Byte)
Permitted
Permitted
Permitted
Read, Write or Erase locked pages
(except page with Lock Byte)
Not Permitted Flash Error Reset
Permitted
Read or Write page containing Lock Byte
(if no pages are locked)
Permitted
Permitted
Permitted
Read or Write page containing Lock Byte
(if any page is locked)
Not Permitted Flash Error Reset
Permitted
Read contents of Lock Byte
(if no pages are locked)
Permitted
Permitted
Permitted
Read contents of Lock Byte
(if any page is locked)
Not Permitted Flash Error Reset
Permitted
Erase page containing Lock Byte
(if no pages are locked)
Permitted Flash Error Reset Flash Error Reset
Erase page containing Lock Byte—Unlock all
pages (if any page is locked)
C2 Device Flash Error Reset Flash Error Reset
Erase Only
Lock additional pages
(change 1s to 0s in the Lock Byte)
Not Permitted Flash Error Reset Flash Error Reset
Unlock individual pages
(change 0s to 1s in the Lock Byte)
Not Permitted Flash Error Reset Flash Error Reset
Read, Write or Erase Reserved Area
Not Permitted Flash Error Reset Flash Error Reset

C2 Device Erase—Erases all Flash pages including the page containing the Lock Byte.
Flash Error Reset—Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is 1 after
reset).
- All prohibited operations that are performed via the C2 interface are ignored (do not cause device reset).
- Locking any Flash page also locks the page containing the Lock Byte.
- Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase.
- If user code writes to the Lock Byte, the Lock does not take effect until the next device reset.
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Rev. 1.4