MC908AB32CFUE Datasheet, PDF (64/392 Pages) Freescale Semiconductor, Inc – Microcontrollers

FLASH Memory
NOTE:
Programming and erasing of FLASH locations cannot be performed by
code being executed from the FLASH memory. While these operations
must be performed in the order shown, other unrelated operations may
occur between the steps. Do not exceed t_PROG maximum. See 23.13
FLASH Memory Characteristics.
4.8 FLASH 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
a block of memory from unintentional erase or program operations due
to system malfunction. This protection is done by using of a FLASH
Block Protect Register (FLBPR). The FLBPR determines the range of
the FLASH memory which is to be protected. The range of the protected
area starts from a location defined by FLBPR and ends at the bottom of
the FLASH memory ($FFFF). When the memory is protected, the HVEN
bit cannot be set in either ERASE or PROGRAM operations.
NOTE:
In performing a program or erase operation, the FLASH block protect
register must be read after setting the PGM or ERASE bit and before
asserting the HVEN bit
When the FLBPR is program 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 the FLBPR are programmed, they lock a block of
memory, address ranges as shown in 4.8.1 FLASH Block Protect
Register. Once the FLBPR is programmed with a value other than $FF,
any erase or program of the FLBPR or the protected block of FLASH
memory is prohibited. The FLBPR itself can be erased or programmed
only with an external voltage, V_TST, present on the IRQ pin. This voltage
also allows entry from reset into the monitor mode.
Technical Data
64
FLASH Memory
MC68HC908AB32 — Rev. 1.1
Freescale Semiconductor