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Serial Communications Modules
SCI
The Serial Communications Interface (SCI) is an independent serial I/O subsystem
(full-duplex UART-type asynchronous system). The SCI can be used for communications
between the microcontroller and a terminal, PC, or other microcontrollers
in the form of a network. An on-chip baud rate generator derives standard
baud-rate frequencies from the microcontroller oscillator. A typical SCI
application is long-distance communications (RS-232).
SCI+
The SCI+ is similar to the SCI with additional support for synchronous serial
communications. A transmitter clock output is used to transfer data synchronously
to SPI like peripherals.
SPI
The Serial Peripheral Interface (SPI) is similar to the SCI, although it
is used to communicate synchronously over shorter distances at up to 4 Mbit/s.
The SPI allows the microcontroller to communicate with peripheral devices,
which could be anything from a simple TTL shift register to a complete subsystem
such as an LCD display or an A/D converter system. The SPI is flexible enough
to interface directly with numerous standard peripherals from many manufacturers.
SPIs can also be used to expand the number of inputs and outputs of the
microcontroller with the minimum number of pins. Typical applications are
in peripheral communications.
SIOP
The Simple Serial I/O Port (SIOP) is a simpler implementation of the SPI.
The serial clock has fixed polarity and no slave select pin is provided.
I2C
The inter-integrated circuit (I2C) is a synchronous bi-directional serial
bus which provides a simple, efficient way for data exchange between devices
at up to 100Kbit/s. The maximum communication distance and number of devices
that can be connected is limited by the maximum bus capacitance of 400pF.
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