mc68hc912bd32 Freescale Semiconductor, Inc, mc68hc912bd32 Datasheet - Page 49

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

Normal
Single-Chip Mode
Special Operating
Modes
Special Expanded
Wide Mode
Special Expanded
Narrow Mode
Special
Single-Chip Mode
3-mode
16-bit locations but this may be preferred over the extra cost of additional
external memory devices.
There are no external address and data buses in this mode. All pins of
ports A, B and E are configured as general-purpose I/O pins. Port E bits
1 and 0 are input-only with internal pullups and the other 22 pins are
bidirectional I/O pins that are initially configured as high-impedance
inputs. Port E pullups are enabled upon reset; port A and B pullups are
disabled upon reset.
There are three special operating modes that correspond to normal
operating modes. These operating modes are commonly used in factory
testing and system development. In addition, there is a special
peripheral mode, in which an external master, such as an I.C. tester, can
control the on-chip peripherals.
This mode can be used for emulation of normal expanded wide mode
and emulation of normal single-chip mode and 16-bit data bus. The bus
control related pins in PORTE are all configured to serve their bus
control output functions rather than general-purpose I/O.
This mode can be used for emulation of normal expanded narrow mode.
In this mode external 16-bit data is handled as two back-to-back bus
cycles, one for the high byte followed by one for the low byte. Internal
operations continue to use full 16-bit data paths.
This mode can be used to force the MCU to active BDM mode to allow
system debug through the BKGD pin. The MCU does not fetch the reset
vector and execute application code as it would in other modes. Instead,
the active background mode is in control of CPU execution and BDM
firmware is waiting for additional serial commands through the BKGD
pin. There are no external address and data buses in this mode. The
MCU operates as a stand-alone device and all program and data space
are on-chip. External port pins can be used for general-purpose I/O.
Freescale Semiconductor, Inc.
For More Information On This Product,
Operating Modes and Resource Mapping
Go to: www.freescale.com
Operating Modes and Resource Mapping
MC68HC912BD32 Rev 1.0
Operating Modes