68HC805P18 Datasheet, PDF (53/111 Pages) Freescale Semiconductor, Inc – SPECIFICATION (General Release)

Freescale Semiconductor, Inc.
GENERAL RELEASE SPECIFICATION
8.3 Programming/Erasing Procedures
To program a byte of EEPROM, set LATCH = CPEN = 1, set ER1 = ER0 = 0, write
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data to the desired address and then set EEPGM for a time, t_EPGM.
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NOTE
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Any bit should be erased before it is programmed. However, if
write/erase cycling is a concern, the following procedure will
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minimize the cycling of each bit in each EEPROM byte.
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If PB • EB = 0, then program the new data over the existing data
without erasing it first. If PB • EB ≠ 0, then erase the byte before
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programming where PB = byte data to be programmed and
EB = existing EEPROM byte data.
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To erase a byte of EEPROM, set LATCH = 1, CPEN = 1, ER1 = 0 and ER0 = 1,
write to the address to be erased and set EEPGM for a time, t_EBYT.
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To erase a block of EEPROM, set LATCH = 1, CPEN = 1, ER1 = 1 and ER0 = 0,
write to any address in the block, and set EEPGM for a time, t_EBLOCK.
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For a bulk erase, set LATCH = 1, CPEN = 1, ER1 = 1, and ER0 = 1, write to any
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address in the array, and set EEPGM for a time, t_EBULK.
To terminate the programming or erase sequence, clear EEPGM, delay for a time
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t_FPV to allow the program voltage to fall, and then clear LATCH and CPEN to free
up the buses. Following each erase or programming sequence, clear all
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programming control bits.
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NOTE
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Erased/programmed state of the programming EEPROM (128 bytes)
and the user EEPROM (8064 bytes) is opposite. An erased
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EEPROM memory location is a logic zero for user EEPROM, while it
is a logic one for programming EEPROM.
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Rev. 1.0
EEPROM
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