MC9S08GB60A Datasheet, PDF (60/302 Pages) Freescale Semiconductor, Inc – HCS08 Microcontrollers

Chapter 4 Memory
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.
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
KEYACC
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-6. Flash Configuration Register (FCNFG)
Table 4-9. 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.
Reads of the flash return invalid data.
4.6.4 Flash Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT is copied from flash into FPROT. Bits 0,
1, and 2 are not used and each always reads as 0. This register may be read at any time, but user program
writes have no meaning or effect. Background debug commands can write to FPROT.
7
6
5
4
3
2
1
0
R FPOPEN
FPDIS
FPS2
FPS1
FPS0
0
0
0
W
(1)
(1)
(1)
(1)
(1)
Reset
This register is loaded from nonvolatile location NVPROT during reset.
= Unimplemented or Reserved
Figure 4-7. Flash Protection Register (FPROT)
1 _{Background commands can be used to change the contents of these bits in FPROT.}
Table 4-10. FPROT Field Descriptions
Field
Description
7
FPOPEN
Open Unprotected Flash for Program/Erase
0 Entire flash memory is block protected (no program or erase allowed).
1 Any flash location, not otherwise block protected or secured, may be erased or programmed.
MC9S08GB60A Data Sheet, Rev. 2
60
Freescale Semiconductor