ColdFire Flash Module (CFM)
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
17-9
17.3.3.3
CFMSEC — CFM Security Register
The CFMSEC register is used to store the flash security word and CFM security state.
CFMSEC register bits [31:30,15:0] are readable, while the remaining bits read 0 and all bits are not
writable.
The CFMSEC register is loaded from the flash configuration field in the flash block at offset 0x0414
during the reset sequence, indicated by F in
IPSBAR
Offset: 0x1D_0008 (CFMSEC)
Access: User read/write
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R KEYEN SECSTAT
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
F
1
1
The reset state for bit 31 is loaded from the flash configuration field at offset 0x0414 during reset (see
-
2
2
Reset state determined by security state of CFM.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
SEC
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 17-6. CFM Security Register (CFMSEC)
Table 17-6. CFMSEC Field Descriptions
Field
Description
31
KEYEN
Enable backdoor key access to unlock security
1 = Backdoor key access to flash module is enabled.
0 = Backdoor key access to flash module is disabled.
30
SECSTAT
Flash memory security status
1 = Flash security is enabled.
0 = Flash security is disabled.
29-16
Reserved, should read 0
15 - 0
SEC
Flash memory security bits
The SEC bits define the security state of the MCU as shown in
, which defines the single code
that enables the security feature in the CFM
Table 17-7. CFM
Security States
SEC[15:0]
Description
0x4AC8
1
1
This value was chosen because it represents the ColdFire HALT instruction, making
it unlikely that a user compiled code accidentally programmed at the security
configuration field location would unintentionally secure the flash memory.
Flash Memory Secured
All other combinations
Flash Memory Unsecured
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60
