AN2156 Freescale Semiconductor / Motorola, AN2156 Datasheet - Page 40

• Manufacturer Part Number: AN2156
• Description: Programming and Erasing FLASH and EEPROM Memories on the MC68HC908AS60A/AZ60A
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
Question 2
Answer 2
40
NOTE:
The COP is always enabled out of RESET and can be disabled by
modifying the “write-once” CONFIG-1 register. Refer to the
Program
I wanted to erase only vector locations using the page erase operation,
but the block protection registers were also erased. Did I do anything
wrong?
No. The block protect registers and vector locations are in the same
page. On the MC68HC908AS60A/AZ60A, programming and erasing the
block protect registers is not protected. (On the
MC68HC908AS60/AZ60, this operation required a high voltage on the
IRQ pin). Therefore, the block protect registers are also erased when the
vector locations are erased. If other FLASH locations must be protected,
you have to reprogram the block protect register after the vector erasing
is completed.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Is the COP enabled?
If the COP is enabled, address $FFFF has to be written
periodically (with any value) to prevent a COP reset. However, this
COP feeding process during the program/erase operation can
cause unintentional FLASH programming or erasing because
address $FFFF exists in the FLASH. To avoid issues, make sure
that the selected COP period is long enough that the COP feeding
process is not performed during the program/erase operation or
disable the COP entirely during this operation.
Was Motorola’s recommended programming algorithm (or erasing
algorithm) used in your code?
The recommended programming algorithm ensures that the
FLASH is programmed for sufficient data retention with a
minimum program time. Not following this algorithm can lead to
overprogramming, which risks program disturb.
Operation.
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FLASH
MOTOROLA
AN2156