NXP Semiconductors MC9S08QL4, Reference Manual

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Chapter 4 Memory
MC9S08QL8 MCU Series Reference Manual, Rev. 1
NXP Semiconductors 53
4.7.3 Flash Configuration Register (FCNFG)
4.7.4 Flash Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT is copied from flash into FPROT. FPROT
can be read at any time. With FPDIS set, all bits are writable, but with FPDIS clear the FPS bits are writable
as long as the size of the protected region is being increased. Any FPROT write that attempts to decrease
the size of the protected region will be ignored.
Figure 4-8. Flash Protection Register (FPROT)
Table 4-9. Security States
1
1
SEC01:SEC00 changes to 1:0 after successful backdoor
key entry or a successful blank check of flash.
SEC01:SEC00 Description
0:0 secure
0:1 secure
1:0 unsecured
1:1 secure
7 6 5 4 3 2 1 0
R 0 0
KEYACC
0 0 0 0 0
W
Reset 0 0 0 0 0 0 0 0
= Unimplemented or Reserved
Figure 4-7. Flash Configuration Register (FCNFG)
Table 4-10. FCNFG Register Field Descriptions
Field Description
5
KEYACC
Enable Writing of Access Key — This bit enables writing of the backdoor comparison key. For more detailed
information about the backdoor key mechanism, refer to Section 4.6, Security .”
0 Writes to 0xFFB0–0xFFB7 are interpreted as the start of a flash programming or erase command.
1 Writes to NVBACKKEY (0xFFB0–0xFFB7) are interpreted as comparison key writes.
7 6 5 4 3 2 1 0
R
FPS
(1)
1
Background commands can be used to change the contents of these bits in FPROT.
FPDIS
(1)
W
Reset This register is loaded from nonvolatile location NVPROT during reset.