C8051F336_08 Datasheet, PDF (94/227 Pages) Silicon Laboratories – Mixed-Signal Byte-Programmable EPROM MCU

C8051F336/7/8/9
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 16.1 summarizes the Flash security
features of the C8051F336/7/8/9 devices.
Table 16.1. Flash Security Summary
Action
Read, Write or Erase unlocked pages
(except page with Lock Byte)
Read, Write or Erase locked pages
(except page with Lock Byte)
Read or Write page containing Lock Byte
(if no pages are locked)
Read or Write page containing Lock Byte
(if any page is locked)
Read contents of Lock Byte
(if no pages are locked)
Read contents of Lock Byte
(if any page is locked)
Erase page containing Lock Byte
(if no pages are locked)
Erase page containing Lock Byte—Unlock all
pages (if any page is locked)
Lock additional pages
(change '1's to '0's in the Lock Byte)
Unlock individual pages
(change '0's to '1's in the Lock Byte)
Read, Write or Erase Reserved Area
C2 Debug
Interface
Permitted
User Firmware executing from:
an unlocked page a locked page
Permitted
Permitted
Not Permitted Flash Error Reset
Permitted
Permitted
Permitted
Permitted
Not Permitted Flash Error Reset
Permitted
Permitted
Permitted
Permitted
Not Permitted Flash Error Reset
Permitted
Permitted Flash Error Reset Flash Error Reset
C2 Device
Erase Only
Not Permitted
Flash Error Reset Flash Error Reset
Flash Error Reset Flash Error Reset
Not Permitted Flash Error Reset Flash Error Reset
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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