
Memory
FLASH-1 Memory (FLASH-1)
MC68HC908GR60A MC68HC908GR48A MC68HC908GR32A
Data Sheet
MOTOROLA
Memory
51
Decreasing the value in FL1BPR by one increases the protected range by one
page (128 bytes). However, programming the block protect register with $FE
protects a range twice that size, 256 bytes, in the corresponding array. $FE means
that locations $FF00–$FFFF are protected in FLASH-1.
The FLASH memory does not exist at some locations. The block protection range
configuration is unaffected if FLASH memory does not exist in that range. Refer to
Figure 2-1 and make sure that the desired locations are protected.
2.6.3 FLASH-1 Block Protection
Due to the ability of the on-board charge pump to erase and program the FLASH
memory in the target application, provision is made for protecting blocks of memory
from unintentional erase or program operations due to system malfunction. This
protection is done by using the FLASH-1 block protection register (FL1BPR).
FL1BPR determines the range of the FLASH-1 memory which is to be protected.
The range of the protected area starts from a location defined by FL1BPR and ends
at the bottom of the FLASH-1 memory ($FFFF). When the memory is protected,
the HVEN bit can not be set in either ERASE or PROGRAM operations.
NOTE:
In performing a program or erase operation, the FLASH-1 block protect register
must be read after setting the PGM or ERASE bit and before asserting the
HVEN bit.
When the FLASH-1 block protect register is programmed with all 0’s, the entire
memory is protected from being programmed and erased. When all the bits are
erased (all 1’s), the entire memory is accessible for program and erase.
When bits within FL1BPR are programmed (0), they lock a block of memory
address ranges as shown in Figure 2-4. If FL1BPR is programmed with any value
other than $FF, the protected block of FLASH memory can not be erased or
programmed.
NOTE:
The vector locations and the FLASH block protect registers are located in the same
page. FL1BPR and FL2BPR are not protected with special hardware or software.
Therefore, if this page is not protected by FL1BPR and the vector locations are
erased by either a page or a mass erase operation, then both FL1BPR and
FL2BPR will also get erased.