mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 33

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

2.6.5 FLASH Protection
MC68HC908QF4 — Rev. 1.0
MOTOROLA
NOTE:
NOTE:
NOTE:
The COP register at location $FFFF should not be written between steps 5-12,
when the HVEN bit is set. Since this register is located at a valid FLASH address,
unpredictable behavior may occur if this location is written while HVEN is set.
This program sequence is repeated throughout the memory until all data is
programmed.
Programming and erasing of FLASH locations cannot be performed by code being
executed from the FLASH memory. While these operations must be performed in
the order shown, other unrelated operations may occur between the steps. Do not
exceed t
Due to the ability of the on-board charge pump to erase and program the FLASH
memory in the target application, provision is made to protect blocks of memory
from unintentional erase or program operations due to system malfunction. This
protection is done by use of a FLASH block protect register (FLBPR). The FLBPR
determines the range of the FLASH memory which is to be protected. The range
of the protected area starts from a location defined by FLBPR and ends to the
bottom of the FLASH memory ($FFFF). When the memory is protected, the HVEN
bit cannot be set in either ERASE or PROGRAM operations.
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 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.
1. The time between each FLASH address change, or the time between the last FLASH address
10. Clear the PGM bit
11. Wait for time, t
12. Clear the HVEN bit.
13. After time, t
programmed to clearing PGM bit, must not exceed the maximum programming time, t
maximum.
7. Write data to the FLASH address being programmed
8. Wait for time, t
9. Repeat step 7 and 8 until all desired bytes within the row are programmed.
again.
Freescale Semiconductor, Inc.
PROG
For More Information On This Product,
maximum, see
Go to: www.freescale.com
RCV
PROG
NVH
(typical 1 µs), the memory can be accessed in read mode
(1)
(minimum 5 µs).
Memory
.
(minimum 30 µs).
17.12 Memory
Characteristics.
FLASH Memory (FLASH)
(1)
.
PROG
Data Sheet
Memory
33