Freescale Semiconductor, Inc.
EEPROM Memory
EEPROM Programmer’s Model
8.4 EEPROM Programmer’s Model
The EEPROM module consists of two separately addressable sections.
The first is a four-byte memory mapped control register block used for
control, testing and configuration of the EEPROM array. The second
section is the EEPROM array itself.
At reset, the four-byte register section starts at address $00F0 and the
EEPROM array is located from addresses $0800 to $0FFF. For
information on re-mapping the register block and EEPROM address
space, refer to Operating Modes.
Read/write access to the memory array section can be enabled or
disabled by the EEON control bit in the INITEE register. This feature
allows the access to memory mapped resources with lower priority than
the EEPROM memory array. EEPROM control registers can be accessed
regardless of the state of EEON. Any EEPROM erase or program
operations already in progress will not be affected by modifying EEON.
Using the normal EEPROG control, it is possible to continue
program/erase operations during WAIT. For lowest power consumption
during WAIT, stop program/erase by turning off EEPGM.
If the STOP mode is entered during programming or erasing,
program/erase voltage will be automatically turned off and the RC clock
(if enabled) is stopped. However, the EEPGM control bit will remain set.
When STOP mode is terminated, the program/erase voltage will be
automatically turned back on if EEPGM is set.
At low bus frequencies, the RC clock must be turned on for
program/erase.
The EEPROM module contains an extra byte called SHADOW byte
which is loaded at reset into the EEMCR register.
To program the SHADOW byte, when in special modes (SMODN=0), the
NOSHB bit in EEMCR register must be cleared. Normal programming
routines are used to program the SHADOW byte which becomes
accessible at address $0FC0 when NOSHB is cleared.
At the next reset the SHADOW byte data is loaded into the EEMCR.
The SHADOW byte can be protected from being programmed or erased
by setting the SHPROT bit of EEPROT register.
MC68HC912DG128 — Rev 3.0
Technical Data
EEPROM Memory
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