Freescale Semiconductor, Inc.
EEPROM-2
Functional Description
b. The EEPGM bit cannot be set if the EELAT bit is cleared and a
non-EEPROM write has occurred. This is to ensure proper
erasing sequence. Once EEPGM is set, the type of erase mode
cannot be modified. If EEPGM is set, the onboard charge pump
generates the erase voltage and applies it to the user EEPROM
array. When the EEPGM bit is cleared, the erase voltage is
removed from the array and the internal charge pump is turned
off.
c. Any attempt to clear both EEPGM and EELAT bits with a single
instruction will only clear EEPGM. This is to allow time for removal
of high voltage from the EEPROM array.
In general, all bits should be erased before being programmed.
However, if program/erase cycling is of concern, minimize bit cycling in
each EEPROM byte. If any bit in a byte requires change from a 0 to a 1,
the byte needs be erased before programming. Table 7-1 summarizes
the conditions for erasing before programming
Table 7-1. EEPROM Program/Erase Cycling Reduction
EEPROM Data To Be
Programmed
EEPROM Data Before
Programming
Erase Before
Programming?
0
0
1
1
0
1
0
1
No
No
Yes
No
MC68HC908AS60 — Rev. 1.0
Technical Data
EEPROM-2
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