MC68HC912B32MFU8 MOTOROLA [Motorola, Inc], MC68HC912B32MFU8 Datasheet - Page 30

• Manufacturer Part Number: MC68HC912B32MFU8
• Description: 16-Bit Microcontroller
• Manufacturer: MOTOROLA [Motorola, Inc]

MISC — Miscellaneous Mapping Control Register
NDRF — Narrow Data Bus for Register-Following Map
RFSTR1, RFSTR0 — Register-Following Stretch Bit 1 and Bit 0
EXSTR1, EXSTR0 — External Access Stretch Bit 1 and Bit 0
MAPROM — Map Location of Flash EEPROM
30
MOTOROLA
RESET:
The 32-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.
This register can be read anytime. In normal modes MISC can be written once; in special modes it can
be written anytime.
This bit enables a narrow bus feature for the 512-byte register-following map. In expanded narrow (eight
bit) modes, single-chip modes, and peripheral mode, NDRF has no effect. The register-following map
always begins at the byte following the 512-byte register map. If the registers are moved this space will
also move.
These bits determine the amount of clock stretch on accesses to the 512-byte register-following map. It
is valid regardless of the state of the NDRF bit. In single-chip and peripheral modes this bit has no
meaning or effect.
These bits determine the amount of clock stretch on accesses to the external address space. In single-
chip and peripheral modes this bit has no meaning or effect.
This bit determines the location of the on-chip Flash EEPROM. In expanded modes it is reset to zero.
In single-chip modes it is reset to one. If ROMON is zero, this bit has no meaning or effect.
0 = Register-following map space acts as a full 16-bit data bus
1 = Register-following map space acts the same as an 8-bit external data bus
0 = Flash EEPROM is located from $0000 to $7FFF
1 = Flash EEPROM is located from $8000 to $FFFF
Bit 7
0
0
NDRF
Stretch Bit RFSTR1 Stretch Bit RFSTR0 E Clocks Stretched
Stretch Bit EXSTR1 Stretch Bit EXSTR0 E Clocks Stretched
6
0
Table 11 Register-Following Stretch-Bit Definition
Table 12 Expanded Stretch-Bit Definition
0
0
1
1
0
0
1
1
RFSTR1
5
0
RFSTR0
4
0
0
1
0
1
0
1
0
1
EXSTR1
3
0
EXSTR0 MAPROM ROMON
2
0
0
1
2
3
0
1
2
3
1
0
MC68HC912B32TS/D
Bit 0
MC68HC912B32
0
$0013