FLASH Memory
10. Wait for time, t
(5 µs).
nvh
11. Clear the HVEN bit.
12. After time, t (1 µs), the memory can be accessed in read mode again.
rcv
This program sequence is repeated throughout the memory until all data is programmed.
NOTE
The time between each FLASH address change (step 6 to step 6), or the
time between the last FLASH addressed programmed to clearing the PGM
bit (step 6 to step 9), must not exceed the maximum programming time,
t
max.
prog
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.
2.5.6 FLASH 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 to protect pages of memory from unintentional erase or program operations
due to system malfunction. This protection is done by use 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 to the bottom of the FLASH memory
($FFFF). When the memory is protected, the HVEN bit cannot be set in either erase or program
operations.
NOTE
The mask option register ($FFCF) and the 48 bytes of user interrupt vectors
($FFD0–$FFFF) are always protected, regardless of the value in the
FLASH block protect register. A mass erase is required to erase these
locations.
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
45
FREESCALE [ Freescale ]
