mc68hc912bl16 Freescale Semiconductor, Inc, mc68hc912bl16 Datasheet - Page 29

• Manufacturer Part Number: mc68hc912bl16
• Description: 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

5.3.2 RAM Mapping
INITRM — Initialization of Internal RAM Position Register
RAM[15:11] — Internal RAM Map Position
5.3.3 EEPROM Mapping
INITEE — Initialization of Internal EEPROM Position Register
EE[15:12] — Internal EEPROM map position
EEON — Internal EEPROM On (Enabled)
5.3.4 Flash EEPROM and Expansion Address Mapping
MC68HC912BL16TS/D
RESET:
RESET:
The MC68HC912BL16 has 512byte of fully static RAM that is used for storing instructions, variables,
and temporary data during program execution. After reset, RAM addressing begins at location $0800
but can be assigned to any 2-Kbyte boundary within the standard 64-Kbyte address space. Mapping of
internal RAM is controlled by five bits in the INITRM register. The RAM array occupies the first 512byte
of the 2-Kbyte block.
These bits specify the upper five bits of the 16-bit RAM address.
Write once in normal modes or anytime in special modes. Read anytime.
The MC68HC912BL16 has 512 bytes of EEPROM which is activated by the EEON bit in the INITEE
register.
Mapping of internal EEPROM is controlled by four bits in the INITEE register. After reset EEPROM ad-
dress space begins at location $0E00 but can be mapped to any 4-Kbyte boundary within the standard
64-Kbyte address space.
These bits specify the upper four bits of the 16-bit EEPROM address.
Write once in normal modes or anytime in special modes. Read anytime.
The EEON bit allows read access to the EEPROM array. EEPROM control registers can be accessed
and EEPROM locations may be programmed or erased regardless of the state of EEON.
This bit is forced to one in single-chip modes. Read or write anytime.
Additional mapping controls are available that can be used in conjunction with Flash EEPROM and
memory expansion.
The 16-Kbyte Flash EEPROM can be mapped to either the upper or lower half of the 64-Kbyte address
space. When mapping conflicts occur, registers, RAM and EEPROM have priority over Flash EEPROM.
To use memory expansion the part must be operated in one of the expanded modes.
0 = Memory mapping interface continues to function during Wait mode.
1 = Memory mapping interface access is shut down during Wait mode.
0 = Removes the EEPROM from the map
1 = Places the on-chip EEPROM in the memory map
RAM15
EE15
Bit 7
Bit 7
0
0
RAM14
EE14
6
0
6
0
Freescale Semiconductor, Inc.
For More Information On This Product,
RAM13
EE13
5
0
5
0
Go to: www.freescale.com
RAM12
EE12
4
0
4
0
RAM11
3
1
3
0
0
2
0
0
2
0
0
1
0
0
1
0
0
EEON
Bit 0
Bit 0
0
0
1
$0010
$0012
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