MC912DG128A Motorola, MC912DG128A Datasheet - Page 113

• Manufacturer Part Number: MC912DG128A
• Description: Microcontrollers
• Manufacturer: Motorola

Special mode
13-eeprom
MOTOROLA
If an existing application code with EEPROM program/erase routines is
fixed and the system is already operating at a known oscillator
frequency, it is recommended to initialize the shadow word with the
corresponding EEDIVH and EEDIVL values in special mode. The
shadow word initializes EEDIVH and EEDIVL registers upon system
reset to ensure software compatibility with existing code. Initializing the
EEDIVH and EEDIVL registers in special modes (SMODN=0) is
accomplished by the following steps.
1. Write correct divider value to EEDIVH and EEDIVL registers
2. Remove the SHADOW word protection by clearing SHPROT bit in
3. Clear NOSHW bit in EEMCR register to make the SHADOW word
4. Write NOSHW bit in EEMCR register to make the SHADOW word
5. Program bits 1 and 0 of the high byte of the SHADOW word and
6. Protect the SHADOW word by setting SHPROT bit in EEPROT
based on the oscillator frequency as per
EEPROT register.
visible at $0FC0-$0FC1.
visible at $0FC0-$0FC1.
bits 7 to 0 of the low byte of the SHADOW word like a regular
EEPROM location at address $0FC0 and $0FC1. Do not program
other bits of the high byte of the SHADOW word (location $0FC0);
otherwise some regular EEPROM array locations will not be
visible. At the next reset, the SHADOW values are loaded into the
EEDIVH and EEDIVL registers. They do not require further
initialization as long as the oscillator frequency of the target
application is not changed.
register.
EEPROM
Programming EEDIVH and EEDIVL Registers
MC68HC912DT128A Rev 2.0
Table
17.
EEPROM
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