XC886 Datasheet, PDF (24/119 Pages) Infineon Technologies AG – 8-Bit Single-Chip Microcontroller

XC886/888CLM
Functional Description
3.2.1 Memory Protection Strategy
The XC886/888 memory protection strategy includes:
• Read-out protection: The user is able to protect the contents in the Flash (for Flash
devices) and ROM (for ROM devices) memory from being read
• Flash program and erase protection (for Flash devices only)
Flash memory protection modes are available only for Flash devices:
• 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.
Table 4
Flash Protection Modes
Mode
0
1
Activation
Program a valid password via BSL mode 6
Selection
MSB of password = 0
MSB of password = 1
P-Flash contents Read instructions in the
can be read by P-Flash
Read instructions in the
P-Flash or D-Flash
P-Flash program Not possible
and erase
Not possible
D-Flash contents Read instructions in any program
can be read by memory
Read instructions in the
P-Flash or D-Flash
D-Flash program Possible
Not possible
D-Flash erase
Possible, on the condition that bit
DFLASHEN in register MISC_CON
is set to 1 prior to each erase
operation
Not possible
BSL mode 6, which is used for enabling Flash protection, can also be used for disabling
Flash protection. Here, the programmed password must be provided by the user. A
password match triggers an automatic erase of the protected P-Flash and D-Flash
contents, including the programmed password. The Flash protection is then disabled
upon the next reset.
Although no protection scheme can be considered infallible, the XC886/888 memory
protection strategy provides a very high level of protection for a general purpose
microcontroller.
Note: If ROM read-out protection is enabled, only read instructions in the ROM memory
can target the ROM contents.
Data Sheet
Prelimary
20
V0.1, 2006-02