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.

last update: 10JUL1997