MC68HC908GP20 Datasheet, PDF (182/406 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

BPR0 — Block Protect Register Bit 0
In a larger memory, this bit would protect the memory contents in the
address range $8000 to $FFFF. It is redundant in this implementation.
Setting this bit locks everything from $B000 to $FFFF.
1 = Address range protected from erase or program
0 = Address range open to erase or program
Bit 7, Bit 6, Bit 5, and Bit 4
These bits do not affect FLASH block protection. They are extra bits
that can be used by the user as readable/writeable bits.
1 = Bit is set
0 = Bit is cleared
By programming the block protect bits, a portion of the memory will be
locked so that no further erase or program operations may be
performed. Programming more than one bit at a time is redundant. If
both BPR3 and BPR2 are set, for instance, the address range $B000
through $FFFF is locked. If all bits are erased, then all of the memory is
available for erase and program. The presence of a voltage V_TST on the
IRQ pin will bypass the block protection so that all of the memory,
including the block protect register, is open for program and erase
operations.
11.10 Wait Mode
Putting the MCU into wait mode while the FLASH is in read mode does
not affect the operation of the FLASH memory directly, but there will not
be any memory activity since the CPU is inactive.
The WAIT instruction should not be executed while performing a
program or erase operation on the FLASH. When the MCU is put into
wait mode, the charge pump for the FLASH is disabled so that either a
program or erase operation will not continue. If the memory is in either
program mode (PGM = 1, HVEN = 1) or erase mode (ERASE = 1,
HVEN = 1), then it will remain in that mode during wait. Exit from wait
must now be done with a reset rather than an interrupt because if exiting
wait with an interrupt, the memory will not be in read mode and the
interrupt vector cannot be read from the memory.
Advance Information
182
MC68HC908GP20 — Rev 2.1
Freescale Semiconductor