mc68hc912bl16 Freescale Semiconductor, Inc, mc68hc912bl16 Datasheet - Page 30

• Manufacturer Part Number: mc68hc912bl16
• Description: 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, 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
RESET:
RESET:
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 $4000 to $7FFF
1 = Flash EEPROM is located from $C000 to $FFFF
Bit 7
0
0
0
NDRF
Stretch Bit RFSTR1 Stretch Bit RFSTR0 E Clocks Stretched
Stretch Bit EXSTR1 Stretch Bit EXSTR0 E Clocks Stretched
6
0
0
Table 11 Register-Following Stretch-Bit Definition
Freescale Semiconductor, Inc.
For More Information On This Product,
Table 12 Expanded Stretch-Bit Definition
0
0
1
1
0
0
1
1
RFSTR1
5
0
0
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RFSTR0
4
0
0
0
1
0
1
0
1
0
1
EXSTR1
3
1
1
EXSTR0 MAPROM ROMON
2
1
1
0
1
2
3
0
1
2
3
1
0
1
MC68HC912BL16TS/D
MC68HC912BL16
Bit 0
0
1
Ex. Modes
Sing. Chip
$0013