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S9S08DZ32F1CLH Datasheet, PDF (63/416 Pages) Freescale Semiconductor, Inc – HC08 instruction set with added BGND instruction | |||
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Chapter 4 Memory
R
W
Reset
7
KEYEN
F
6
5
4
3
2
1
0
FNORED EPGMOD
0
0
0
SEC
F
F
0
0
0
F
F
= Unimplemented or Reserved
F = loaded from nonvolatile location NVOPT during reset
Figure 4-6. Flash and EEPROM Options Register (FOPT)
Table 4-9. FOPT Register Field Descriptions
Field
Description
7
KEYEN
Backdoor Key Mechanism Enable â When this bit is 0, the backdoor key mechanism cannot be used to
disengage security. The backdoor key mechanism is accessible only from user (secured) ï¬rmware. BDM
commands cannot be used to write key comparison values that would unlock the backdoor key. For more detailed
information about the backdoor key mechanism, refer to Section 4.5.9, âSecurity.â
0 No backdoor key access allowed.
1 If user ï¬rmware writes an 8-byte value that matches the nonvolatile backdoor key (NVBACKKEY through
NVBACKKEY+7 in that order), security is temporarily disengaged until the next MCU reset.
6
FNORED
Vector Redirection Disable â When this bit is 1, then vector redirection is disabled.
0 Vector redirection enabled.
1 Vector redirection disabled.
5
EPGMOD
EEPROM Sector Mode â When this bit is 0, each sector is split into two pages (4-byte mode). When this bit is
1, each sector is in a single page (8-byte mode).
0 Half of each EEPROM sector is in Page 0 and the other half is in Page 1.
1 Each sector is in a single page.
1:0
SEC
Security State Code â This 2-bit ï¬eld determines the security state of the MCU as shown in Table 4-10. When
the MCU is secure, the contents of RAM, EEPROM and Flash memory cannot be accessed by instructions from
any unsecured source including the background debug interface. SEC changes to 1:0 after successful backdoor
key entry or a successful blank check of Flash. For more detailed information about security, refer to Section
4.5.9, âSecurity.â
Table 4-10. Security States1
SEC[1:0]
Description
0:0
secure
0:1
secure
1:0
unsecured
1:1
secure
1 SEC changes to 1:0 after successful backdoor key entry
or a successful blank check of Flash.
MC9S08DZ60 Series Data Sheet, Rev. 4
Freescale Semiconductor
63
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