Memory
FLASH Memory (FLASH)
MC68HC908QF4 — Rev. 1.0
Data Sheet
MOTOROLA
Memory
31
ERASE — Erase Control Bit
This read/write bit configures the memory for erase operation. ERASE is
interlocked with the PGM bit such that both bits cannot be equal to 1 or set to 1
at the same time.
1 = Erase operation selected
0 = Erase operation unselected
PGM — Program Control Bit
This read/write bit configures the memory for program operation. PGM is
interlocked with the ERASE bit such that both bits cannot be equal to 1 or set to
1 at the same time.
1 = Program operation selected
0 = Program operation unselected
2.6.2 FLASH Page Erase Operation
Use the following procedure to erase a page of FLASH memory. A page consists
of 64 consecutive bytes starting from addresses $XX00, $XX40, $XX80, or $XXC0.
The 48-byte user interrupt vectors area also forms a page. Any FLASH memory
page can be erased alone.
1.
Set the ERASE bit and clear the MASS bit in the FLASH control register.
2.
Read the FLASH block protect register.
3.
Write any data to any FLASH location within the address range of the block
to be erased.
4.
Wait for a time, tNVS (minimum 10 s).
5.
Set the HVEN bit.
6.
Wait for a time, tErase (minimum 1 ms or 4 ms).
7.
Clear the ERASE bit.
8.
Wait for a time, tNVH (minimum 5 s).
9.
Clear the HVEN bit.
10.
After time, tRCV (typical 1 s), the memory can be accessed in read mode
again.
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 as shown, but other unrelated operations may occur between the steps.
In applications that need up to 10,000 program/erase cycles, use the 4 ms page
erase specification to get improved long-term reliability. Any application can use
this 4 ms page erase specification. However, in applications where a FLASH
location will be erased and reprogrammed less than 1000 times, and speed is
important, use the 1 ms page erase specification to get a lower minimum erase
time.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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