MC908AZ32ACFUE Datasheet, PDF (45/324 Pages) Freescale Semiconductor, Inc – Microcontrollers

FLASH Control and Block Protect Registers
4.3.2 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 FLASH programming sequence. The value in this register
determines the starting location of the protected range within the FLASH memory.
Address:
Read:
Write:
$FF80
Bit 7
6
5
4
3
2
1
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
Figure 4-2. FLASH Block Protect Register (FLBPR)
Bit 0
BPR0
FLBPR[7:0] — Block Protect Register Bit7 to Bit0
These eight bits represent bits [14:7] of a 16-bit memory address. Bit-15 is logic 1 and bits [6:0] are
logic 0s.
The resultant 16-bit address is used for specifying the start address of the FLASH memory for block
protection. 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 and $XX80 (128 byte page boundaries) within
the FLASH array.
Start address of FLASH block protect 1
16-bit memory address
FLBPR value
0000000
Figure 4-3. FLASH Block Protect Start Address
FLASH Protected Ranges:
FLBPR[7:0]
$FF
$FE
$FD
Protected Range
No Protection
$FF00 – $FFFF
$FE80 – $FFFF
$0B
$8580 – $FFFF
$0A
$8500 – $FFFF
$09
$8480 – $FFFF
$08
$8400 – $FFFF
$04
$8200 – $FFFF
$03
$8180 – $FFFF
$02
$8100 – $FFFF
$01
$8080 – $FFFF
$00
$8000 – $FFFF
MC68HC908AZ32A Data Sheet, Rev. 2
Freescale Semiconductor
45