mc68hc912bd32 Freescale Semiconductor, Inc, mc68hc912bd32 Datasheet - Page 48

• Manufacturer Part Number: mc68hc912bd32
• Description: 16-bit Device Composed Of Standard On-chip Peripherals
• Manufacturer: Freescale Semiconductor, Inc

Normal Operating
Modes
Normal Expanded
Wide Mode
Normal Expanded
Narrow Mode
Operating Modes and Resource Mapping
MC68HC912BD32 Rev 1.0
BKGD MODB MODA
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Reserved (Forced to Peripheral)
There are two basic types of operating modes:
Normal modes — some registers and bits are protected against
accidental changes.
Special modes — allow greater access to protected control registers and
bits for special purposes such as testing and emulation.
A system development and debug feature, background debug mode
(BDM), is available in all modes. In special single-chip mode, BDM is
active immediately after reset.
These modes provide three operating configurations. Background
debugging is available in all three modes, but must first be enabled for
some operations by means of a BDM command. BDM can then be made
active by another BDM command.
This is a normal mode of operation in which the address and data are
multiplexed onto ports A and B. ADDR[15:8] and DATA[15:8] are
present on port A. ADDR[7:0] and DATA[7:0] are present on port B.
Port A is configured as the high byte of address multiplexed with the 8-bit
data bus. Port B is configured as the lower 8-bit address bus. This mode
is used for lower cost production systems that use 8-bit wide external
EEPROMs or RAMs. Such systems take extra bus cycles to access
Special Expanded Narrow
Normal Expanded Narrow
Freescale Semiconductor, Inc.
Special Expanded Wide
Normal Expanded Wide
Special Single Chip
Normal Single Chip
For More Information On This Product,
Special Peripheral
Operating Modes and Resource Mapping
Table 10 Mode Selection
Mode
Go to: www.freescale.com
ADDR[15:8]/DATA[7:0]
ADDR[15:8]/DATA[7:0]
General Purpose I/O
General Purpose I/O
ADDR/DATA
ADDR/DATA
ADDR/DATA
Port A
—
General Purpose I/O
General Purpose I/O
ADDR/DATA
ADDR/DATA
ADDR/DATA
ADDR[7:0]
ADDR[7:0]
Port B
—
2-mode