Datasheet
Chapter 4 Memory
MC9S08LC60 Series Data Sheet: Technical Data, Rev. 4
58 Freescale Semiconductor
4.6.3 FLASH Configuration Register (FCNFG)
Bits 7 through 5 may be read or written at any time. Bits 4 through 0 always read 0 and cannot be written.
4.6.4 FLASH Protection Register (FPROT and NVPROT)
The FPROT register defines which FLASH sectors are protected against program and erase operations.
The FPROT register is also used to determine whether FLASH protection is disabled.
During the reset sequence, the FPROT register is loaded from the nonvolatile location NVPROT. To
change the protection that will be loaded during the reset sequence, the sector containing NVPROT must
be unprotected and erased, then NVPROT can be reprogrammed. With FPDIS set all FPROT 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 write to FPROT that attempts to decrease the size of the protected memory will be ignored.
Trying to alter data in any protected area will result in a protection violation error and the FPVIOL flag
will be set in the FSTAT register. Mass erase is not possible if any one of the sectors is protected.
In order to change the data flash block protection on a temporary basis, the FPROT register EPS bits can
be written to. To change the data flash block protection that will be loaded during the reset sequence, the
Table 4-9. Security States
SEC01:SEC00 Description
0:0 secure
0:1
1
1
The 0:1 bit pattern is the recommended value to be used since it requires two
bit changes before going to the unsecured state.
secure
1:0 unsecured
1:1 secure
76543210
R0 0
KEYACC
00000
W
Reset 00000000
= Unimplemented or Reserved
Figure 4-7. FLASH Configuration Register (FCNFG)
Table 4-10. FCNFG 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 4.5, “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.