MC912DG128A Motorola, MC912DG128A Datasheet - Page 112

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

Programming EEDIVH and EEDIVL Registers
Normal mode
EEPROM
MC68HC912DT128A Rev 2.0
112
CAUTION:
The EEDIVH and EEDIVL registers must be correctly set according to
the oscillator frequency before any EEPROM location can be
programmed or erased.
The EEDIVH and EEDIVL registers are write once in normal mode.
Upon system reset, the application program is required to write the
correct divider value to EEDIVH and EEDIVL registers based on the
oscillator frequency. After the first write, the value in the EEDIVH and
EEDIVL registers is locked from being overwritten until the next reset.
The EEPROM is then ready for standard program/erase routines.
Runaway code can possibly corrupt the EEDIVH and EEDIVL registers
if they are not initialized (write once registers).
1. Reserved for testing. Must be set to one in user application.
2. Reserved. Must be set to one in user application for future compatibility.
Shadow word location
$_FC0, bit 3:2
$_FC0, bit 1:0
$_FC1, bit 7:0
$_FC0, bit 6
$_FC0, bit 5
$_FC0, bit 4
$_FC0 bit 7
Table 20 Shadow word mapping
EEPROM
EEMCR / NOBDML
EEMCR / NOSHW
EEMCR / bit 5
EEMCR / bit 4
EEDIVH / bit 1:0
EEMCR / bit 7:0
not mapped
Register / Bit
(2))
(1)
(1)
MOTOROLA
12-eeprom