mc68hc908gr8b Freescale Semiconductor, Inc, mc68hc908gr8b Datasheet - Page 42

• Manufacturer Part Number: mc68hc908gr8b
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Memory
2.6.7 FLASH Block Protect Register
The FLASH block protect register (FLBPR) 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 location of the protected range within the FLASH memory.
BPR[7:0] — FLASH Block Protect Bits
42
These eight bits represent bits [13:6] of a 16-bit memory address.
Bit 15 and Bit 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, and $XXC0 (64 bytes
page boundaries) within the FLASH memory.
Address:
Reset:
Read:
Write:
START ADDRESS OF FLASH
Write to this register is by a programming sequence to the FLASH memory.
$FC (1111 1100)
$FD (1111 1101)
$FE (1111 1110)
$81 (1000 0001)
$82 (1000 0010)
$FF7E
BPR7
Bit 7
BPR[7:0]
Figure 2-5. FLASH Block Protect Register (FLBPR)
Table 2-2. Examples of Protect Address Ranges
Figure 2-6. FLASH Block Protect Start Address
$FF
$00
BLOCK PROTECT
BPR6
6
MC68HC908GR8B Data Sheet, Rev. 3.0
Unaffected by reset. Initial value from factory is 1.
1
BPR5
5
1
The entire FLASH memory is not protected.
$E040 (1110 0000 0100 0000) — $FFFF
$E080 (1110 0000 1000 0000) — $FFFF
$FF40 (1111 1111 0100 0000) — $FFFF
The entire FLASH memory is protected.
$FF00 (1111 1111 0000 0000) — FFFF
$FF80 (1111 1111 1000 0000) — FFFF
and so on...
FLBPR and vectors are protected
Addresses of Protect Range
BPR4
FLBPR VALUE
4
16-BIT MEMORY ADDRESS
Vectors are protected
BPR3
3
BPR2
0 0 0 0 0 0
2
BPR1
1
Freescale Semiconductor
BPR0
Bit 0