
XC878CLM
Functional Description
Advance Information
Data Sheet
22
V0.1, 2008-04
3.2.1
Memory Protection Strategy
The XC878 memory protection strategy includes:
Basic protection: The user is able to block any external access via the boot option to
any memory
Read-out protection: The user is able to protect the contents in the Flash
Flash program and erase protection
These protection strategies are enabled by programming a valid password (16-bit non-
one value) via Bootstrap Loader (BSL) mode 6.
3.2.1.1
Flash Memory Protection
As long as a valid password is available, all external access to the device, including the
Flash, will be blocked.
For additional security, the Flash hardware protection can be enabled to implement a
second layer of read-out protection, as well as to enable program and erase protection.
Flash hardware protection is available only for Flash devices and comes in two modes:
Mode 0: Only the P-Flash is protected; the D-Flash is unprotected
Mode 1: Both the P-Flash and D-Flash are protected
The selection of each protection mode and the restrictions imposed are summarized in
Table 4
Flash Protection Modes
Flash
Protection
Without hardware
protection
With hardware protection
Hardware
Protection
Mode
-0
1
Activation
Program a valid password via BSL mode 6
Selection
Bit 13 of password = 0
Bit 13 of password = 1
MSB of password = 0
Bit 13 of password = 1
MSB of password = 1
P-Flash
contents
can be read
by
Read instructions in
any program memory
Read instructions in
the P-Flash
Read instructions in
the P-Flash or D-
Flash
External
access to P-
Flash
Not possible