MC68HC08AZ16 Datasheet, PDF (44/527 Pages) Motorola, Inc – HCMOS Microcontroller Unit

EEPROM
programming
EEPROM
Functional description
The unprogrammed state is a logic ‘1’. Programming changes the state
to a logic ‘0’. Only valid EEPROM bytes in the non-protected blocks and
EENVR can be programmed. When the array is configured in the
redundant mode, programming the first 256 bytes will also program the
last 256 bytes with the same data. It is recommended that the EEPROM
be programmed in the non-redundant mode and that the data is
programmed to both locations before entering the redundant mode.
The following procedure describes how to program a byte of EEPROM:
1. Clear EERAS1 and EERAS0 and set EELAT in the EECR
(See Note A. and B.)
2. Write the desired data to any user EEPROM address.
3. Set the EEPGM bit. (See Note C.)
4. Wait for a time, t_EEPGM, to program the byte.
5. Clear EEPGM bit.
6. Wait for the programming voltage time to fall (t_EEFPV).
7. Clear EELAT bits. (See Note D.)
8. Repeat steps 1 to 7 for more EEPROM programming.
NOTES:
A. EERAS1 and EERAS0 must be cleared for programming,
otherwise the part will be in erase mode
B. Setting the EELAT bit configures the address and data buses
to latch data for programming the array. Only data with a valid
EEPROM address will be latched. If another consecutive valid
EEPROM write occurs, this address and data will override the
previous address and data. Any attempts to read other
EEPROM data will result in the latched data being read. If
EELAT is set, other writes to the EECR will be allowed after a
valid EEPROM write.
C. The EEPGM bit cannot be set if the EELAT bit is cleared and
a non-EEPROM write has occurred. This is to ensure proper
programming sequence. When EEPGM is set, the on-board
charge pump generates the program voltage and applies it to
3-eeprom
MOTOROLA
EEPROM
MC68HC08AZ32
43