Introduction
MOTOROLA
MPC801 USER’S MANUAL
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1.2.4 The I2C
The I
C controller is a synchronous, multimaster bus that is used to connect several
integrated circuits on a board. It uses two wires to carry information between the integrated
circuits that are connected to the bus. The I
C controller consists of transmitter and receiver
sections, an independent baud rate generator, and a control unit. The transmitter and
receiver sections use the same clock that is derived from the I
generator in master mode and generated externally in slave mode.
Controller
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2
C controller baud rate
1.2.5 The Serial Peripheral Interface Controller
The serial peripheral interface (SPI) is a full-duplex, synchronous, character-oriented
channel that supports a four-wire interface (receive, transmit, clock and slave select). The
serial peripheral interface block consists of transmitter and receiver sections, an
independent baud rate generator, and a control unit. The transmitter and receiver sections
use the same clock that is derived from the SPI baud rate generator in master mode and
generated externally in slave mode. During an serial peripheral interface transfer, data is
simultaneously transmitted and received.
1.3 POWER MANAGEMENT
The MPC801 supports a wide range of power management features, including full-on, doze,
sleep, deep sleep, and low-power stop. In full-on mode, the MPC801 processor is fully
powered with all internal units operating at full speed. A gear mode is provided that allows
the operating system to reduce the operational frequency of the processor. Doze mode
disables core functional units, except for the timebase, decrementer, phase locked loop,
memory controller, and real-time clock. Sleep mode disables everything, except the real-
time clock and periodic interrupt timer, thus leaving the phase locked loop active for quick
wake-up. The deep sleep mode disables the phase locked loop for low-power, but at the
expense of a slower wake-up. Low-power stop disables all logic in the processor (except the
minimum logic required to restart the device) and lowers the power consumption, but it also
requires the longest wake-up time.
1.4 MPC801 APPLICATIONS
The MPC801 device is specifically designed to be a general-purpose, low-cost entry point
to the embedded PowerPC Family at Motorola. The device excels in applications that
require the performance of a single-issue PowerPC core with moderate amounts of data and
instruction cache. It can support alternate bus masters in addition to providing all the basic
features of glueless memory connections, but does not provide much in the way of serial
connectivity. Instead, it supplies simple UART serial channels as well as I
peripheral interface channels for onboard communication to other peripheral chips.
2
C and serial
The MPC801 excels in low-power and portable applications because of its expansive
power-down modes. In addition, the normal operation current is low. The MPC801 is ideal
for applications where a significant portion of your added value is in peripherals or ASICs
and a low-cost general-purpose core is required. The programmable flexibility of the
memory controller ensures that the board design can accommodate future memory types
without hardware changes, thus enabling the ASIC to concentrate on other system goals.