Datasheet

Memory

MC68HC908QY/QT Family Data Sheet, Rev. 6

38 Freescale Semiconductor

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.

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.

Figure 2-6. FLASH Block Protect Start Address

Address: $FFBE

Bit 7654321Bit 0

Read:

BPR7 BPR6 BPR5 BPR4 BPR3 BPR2 BPR1 BPR0

Write:

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)

Table 2-2. Examples of Protect Start Address

BPR[7:0] Start of Address of Protect Range

$00–$B8 The entire FLASH memory is protected.

$B9 (1011 1001) $EE40 (1110 1110 0100 0000)

$BA (1011 1010) $EE80 (1110 1110 1000 0000)

$BB (1011 1011) $EEC0 (1110 1110 1100 0000)

$BC (1011 1100) $EF00 (1110 1111 0000 0000)

and so on...

$DE (1101 1110)$F780 (1111 0111 1000 0000)

$DF (1101 1111)$F7C0 (1111 0111 1100 0000)

$FE (1111 1110)

$FF80 (1111 1111 1000 0000)

FLBPR, internal oscillator trim values, and vectors are protected

$FF The entire FLASH memory is not protected.

00011

FLBPR VALUE

START ADDRESS OF

16-BIT MEMORY ADDRESS

FLASH BLOCK PROTECT