Freescale Semiconductor, Inc.
1.1.1 Organization
The M68300 family of integrated processors and controllers is built on an M68000 core
processor, an on-chip bus, and a selection of intelligent peripherals appropriate for a set of
applications. The CPU32 is a powerful central processor with nearly the performance of
the MC68020. A system integration module incorporates the external bus interface and
many of the smaller circuits that typically surround a microprocessor for address decoding,
wait-state insertion, interrupt prioritization, clock generation, arbitration, watchdog timing,
and power-on reset timing.
Each member of the M68300 family is distinguished by its selection of peripherals.
Peripherals are chosen to address specific applications but are often useful in a wide
variety of applications. The peripherals may be highly sophisticated timing or protocol
engines that have their own processors, or they may be more traditional peripheral
functions, such as UARTs and timers. Since each major function is designed in a
standalone module, each module might be found in many different M68300 family parts.
Driver software written for a module on one M68300 part can be used to run the same
module that appears on another part.
1.1.2 Advantages
By incorporating so many major features into a single M68300 family chip, a system
designer can realize significant savings in design time, power consumption, cost, board
space, pin count, and programming. The equivalent functionality can easily require 20
separate components. Each component might have 16–64 pins, totaling over 350
connections. Most of these connections require interconnects or are duplications. Each
connection is a candidate for a bad solder joint or misrouted trace. Each component is
another part to qualify, purchase, inventory, and maintain. Each component requires a
share of the printed circuit board. Each component draws power—often to drive large
buffers to get the signal to another chip. The cumulative power consumption of all the
components must be available from the power supply. The signals between the CPU and
a peripheral might not be compatible nor run from the same clock, requiring time delays or
other special design considerations.
In a M68300 family component, the major functions and glue logic are all properly
connected internally, timed with the same clock, fully tested, and uniformly documented.
Power consumption stays well under a watt, and a special standby mode drops current
well under a milliamp during idle periods. Only essential signals are brought out to pins.
The primary package is the surface-mount quad flat pack for the smallest possible
footprint; pin grid arrays are also available.
1.2 CENTRAL PROCESSOR UNIT
The CPU32 is a powerful central processor that supervises system functions, makes
decisions, manipulates data, and directs I/O. A special debugging mode simplifies
processor emulation during system debug.
MOTOROLA
MC68340 USER’S MANUAL
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