MC68HC912BL16 Datasheet, PDF (29/128 Pages) Freescale Semiconductor, Inc – 16-Bit Microcontroller

Freescale Semiconductor, Inc.
0 = Memory mapping interface continues to function during Wait mode.
1 = Memory mapping interface access is shut down during Wait mode.
5.3.2 RAM Mapping
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.
INITRM — Initialization of Internal RAM Position Register
Bit 7
6
5
4
3
2
1
RAM15 RAM14 RAM13 RAM12 RAM11
0
0
RESET:
0
0
0
0
1
0
0
RAM[15:11] — Internal RAM Map Position
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.
$0010
Bit 0
0
0
5.3.3 EEPROM Mapping
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.
INITEE — Initialization of Internal EEPROM Position Register
Bit 7
6
5
4
3
2
EE15
EE14
EE13
EE12
0
0
RESET:
0
0
0
0
0
0
$0012
1
Bit 0
0
EEON
0
1
EE[15:12] — Internal EEPROM map position
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.
EEON — Internal EEPROM On (Enabled)
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.
0 = Removes the EEPROM from the map
1 = Places the on-chip EEPROM in the memory map
5.3.4 Flash EEPROM and Expansion Address Mapping
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.
MC68HC912BL16TS/D
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