C8051F54X_14 Datasheet, PDF (120/275 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F54x
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 14.1 summarizes the Flash security
features of the C8051F54x devices.
Table 14.1. 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)
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 1s to 0s in the Lock Byte)
Unlock individual pages
(change 0s to 1s in the Lock Byte)
Read, Write or Erase Reserved Area
Permitted
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
See note
See note
Note: Flash Reads will return indeterminate data. Flash Writes and Erases are ignored.
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. 1.1