MC68HC908QB8 Datasheet, PDF (36/236 Pages) Freescale Semiconductor, Inc – To provide the most up-to-date information, the revision of our documents

Memory
2.6.6 FLASH Block Protect Register
The FLASH block protect register is implemented as a byte within the FLASH memory, and therefore can
only be written during a programming sequence of the FLASH memory. The value in this register
determines the starting address of the protected range within the FLASH memory.
Read:
Write:
Bit 7
BPR7
6
BPR6
5
BPR5
4
BPR4
3
BPR3
2
BPR2
1
BPR1
Reset:
Unaffected by reset. Initial value from factory is 1.
Write to this register is by a programming sequence to the FLASH memory.
Figure 2-5. FLASH Block Protect Register (FLBPR)
Bit 0
BPR0
BPR[7:0] — FLASH Protection Register Bits [7:0]
These eight bits in FLBPR represent bits [13:6] of a 16-bit memory address. Bits [15:14] are 1s and
bits [5:0] are 0s.
The resultant 16-bit address is used for specifying the start address of the FLASH memory for block
protection. The FLASH is protected from this start address to the end of FLASH memory, at $FFFF.
With this mechanism, the protect start address can be XX00, XX40, XX80, or XXC0 within the FLASH
memory. See Figure 2-6 and Table 2-2.
START ADDRESS OF _{1 1}
FLASH BLOCK PROTECT
16-BIT MEMORY ADDRESS
FLBPR VALUE
0 00000
Figure 2-6. FLASH Block Protect Start Address
Table 2-2. Examples of Protect Start Address
BPR[7:0]
$00–$77
$78 (0111 1000)
$79 (0111 1001)
$7A (0111 1010)
$7B (0111 1011)
$DE (1101 1110)
$DF (1101 1111)
$FE (1111 1110)
$FF
Start of Address of Protect Range
The entire FLASH memory is protected.
$DE00 (1101 1110 0000 0000)
$DE40 (1101 1110 0100 0000)
$DE80 (1101 1110 1000 0000)
$DFC0 (1101 1110 1100 0000)
and so on...
$F780 (1111 0111 1000 0000)
$F7C0 (1111 0111 1100 0000)
$FF80 (1111 1111 1000 0000)
FLBPR, OSCTRIM, and vectors are protected
The entire FLASH memory is not protected.
MC68HC908QB8 Data Sheet, Rev. 1
36
Freescale Semiconductor