MC9S08RC8 Datasheet, PDF (52/234 Pages) Freescale Semiconductor, Inc – Microcontrollers

Memory
7
6
5
4
3
2
1
0
R
KEYACC
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-7. FLASH Configuration Register (FCNFG)
Table 4-8. 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 $FFB0–$FFB7 are interpreted as the start of a FLASH programming or erase command.
1 Writes to NVBACKKEY ($FFB0–$FFB7) 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 at $1824.
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 4-8. FLASH Protection Register (FPROT)
1. Background commands can be used to change the contents of these bits in FPROT.
Table 4-9. FPROT Field Descriptions
Field
Description
7
FPOPEN
6
FPDIS
5:3
FPS[2:0]
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.
FLASH Protection Disable
0 FLASH block specified by FPS2:FPS0 is block protected (program and erase not allowed).
1 No FLASH block is protected.
FLASH Protect Size Selects — When FPDIS = 0, this 3-bit field determines the size of a protected block of
FLASH locations at the high address end of the FLASH (see Table 4-10 and Table 4-11). Protected FLASH
locations cannot be erased or programmed.
MC9S08RC/RD/RE/RG Data Sheet, Rev. 1.11
52
Freescale Semiconductor