XC886/888CLM
Memory Organization
User’s Manual
3-8
V1.3, 2010-02
Memory Organization, V 1.2
Note: For ROM devices, bits 5 to 7 are not applicable and should be written with zeros.
Setting bit 4 enables the protection of D-Flash from accidental erase, i.e.
DFLASHEN bit must be set prior to each erase operation.
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.
For the ROM device, the ROM is protected at all times and BSL mode 6 is used only to
block external access to the device. However, unlike the Flash device, it is not possible
to disable the memory protection of the ROM device. Here, entering BSL mode 6 will
result in a protection error.
Note: If ROM read-out protection is enabled, only read instructions in the ROM memory
can target the ROM contents.
Table 3-2
User Programmable Password Bit Fields
Bits
Size
Usage
Value
7
1-bit
Flash hardware
protection mode
selection bit
0
Flash hardware protection mode 0 is
selected.
1
Flash hardware protection mode 1 is
selected.
6:5
2-bit
Select field for Flash
banks to be erased
during unprotection
00
Only P-Flash banks are erased during
unprotection.
01
P-Flash banks and D-Flash bank 0 are
erased during unprotection.
10
P-Flash banks and D-Flash bank 1 are
erased during unprotection.
11
All Flash banks (P-Flash and D-Flash)
are erased during unprotection.
Note: If bit 7 of password is set, all Flash
banks will be erased during
unprotection, regardless of the value
of bits 4 to 6.
4
1-bit
Flash hardware
protection enable bit
0
Flash hardware protection will not be
activated.
1
Flash hardware protection will be
activated.
3:0
4-bit
User-defined password
field
This password field must be a non-zero
value.
*