Chapter 21 64 KB Flash Module (S12ZFTMRZ64K2KV2)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
Freescale Semiconductor
709
21.3.2.9.1
P-Flash Protection Restrictions
The general guideline is that P-Flash protection can only be added and not removed.
specifies
all valid transitions between P-Flash protection scenarios. Any attempt to write an invalid scenario to the
FPROT register will be ignored. The contents of the FPROT register reflect the active protection scenario.
See the FPHS and FPLS bit descriptions for additional restrictions.
21.3.2.10 EEPROM Protection Register (DFPROT)
The DFPROT register defines which EEPROM sectors are protected against program and erase
operations.
The (unreserved) bits of the DFPROT register are writable with the restriction that protection can be added
but not removed. Writes must increase the DPS value and the DPOPEN bit can only be written from 1
(protection disabled) to 0 (protection enabled). If the DPOPEN bit is set, the state of the DPS bits is
irrelevant.
During the reset sequence, fields DPOPEN and DPS of the DFPROT register are loaded with the contents
of the EEPROM protection byte in the Flash configuration field at global address 0xFF_FE0D located in
P-Flash memory (see
) as indicated by reset condition F in
. To change the
Table 21-23. P-Flash Protection Scenario Transitions
From
Protection
Scenario
To Protection Scenario
(1)
1. Allowed transitions marked with X, see
for a definition of the scenarios.
0
1
2
3
4
5
6
7
0
X
X
X
X
1
X
X
2
X
X
3
X
4
X
X
5
X
X
X
X
6
X
X
X
X
7
X
X
X
X
X
X
X
X
Offset Module Base + 0x0009
7
6
5
4
3
2
1
0
R
DPOPEN
0
DPS[5:0]
W
Reset
F
(1)
1. Loaded from Flash configuration field, during reset sequence.
F
F
F
Figure 21-15. EEPROM Protection Register (DFPROT)
