XC2200 Derivatives
System Units (Vol. 1 of 2)
Memory Organization
User’s Manual
3-40
V2.1, 2008-08
MemoryX2K, V1.3
The command “
” sets RPRODIS to 1 if the correct passwords
that are stored in SecP0 are supplied. If incorrect passwords are entered the bit PROER
is set and RPRODIS stays unchanged. As protection against “brute force attacks” that
search the correct password the password detection is locked. So after supplying the
first incorrect password all following passwords even the correct ones are rejected with
PROER. This state is only left by an Application Reset or by erasing SecP0.
The disabled protection can be enabled again by the Application Reset or by the
command “
Re-Enable Read/Write Protection
” which clears RPRODIS again.
The bit PROER can be reset by an Application Reset or by the commands “
” and “Clear Status”.
The command “
” sets WPRODIS to 1 if the correct passwords
are supplied. It behaves analog to RPRODIS as described above.
The command “
Re-Enable Read/Write Protection
” clears RPRODIS and WPRODIS.
The commands “
”, “
”, “
“
” and “
” set PROER if the write access to the
addressed range is not allowed. If a write access is allowed or not is determined by the
next level.
summarizes how the “Flash State” of protection determines the RPA and WPA
fields of IMB_IMBCTR. For the double bits a short notation is used here and in the
following sections: 1 means active, 0 means inactive, ‘#’ means invalid and ‘–’ means do
not care including invalid states. The symbol ‘|’ means logic or.
Table 3-4
“Flash State” Determining RPA and WPA
IMB_
FSR.
PROI
N
IMB_
FSR.
PROI
NER
IMB_
FSR.
RPR
O
IMB_
FSR.
RPR
ODIS
IMB_
FSR.
WPR
ODIS
Resulting Security Level in RPA and WPA
0
0
–
–
–
Non-protected state:
RPA = 0, WPA = 0.
1
0
Protection installed state (possibly disabled,
see below):
0
–
0
RPA = 0, WPA = 1.
0
0
1
RPA = 0, WPA = 0.
1 | #
0
0
RPA = 1, WPA = 1.
–
1
1
RPA = 0, WPA = 0 (all disabled).
1 | #
0
1
RPA = 1, WPA = 0.
1 | #
1
0
RPA = 0, WPA = 1.