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10.8 LINSCI SERIAL COMMUNICATION INTERFACE (LIN Master Only)
10.8.1 Introduction
The Serial Communications Interface (SCI) offers
a flexible means of full-duplex data exchange with
external equipment requiring an industry standard
NRZ asynchronous serial data format. The SCI of-
fers a very wide range of baud rates using two
baud rate generator systems.
10.8.2 Main Features
■ Full duplex, asynchronous communications
■ NRZ standard format (Mark/Space)
■ Dual baud rate generator systems
■ Independently
programmable
transmit
and
receive baud rates up to 500K baud.
■ Programmable data word length (8 or 9 bits)
■ Receive buffer full, Transmit buffer empty and
End of Transmission flags
■ 2 receiver wake-up modes:
– Address bit (MSB)
– Idle line
■ Muting function for multiprocessor configurations
■ Separate
enable bits for Transmitter and
Receiver
■ 4 error detection flags:
– Overrun error
– Noise error
– Frame error
– Parity error
■ 5 interrupt sources with flags:
– Transmit data register empty
– Transmission complete
– Receive data register full
– Idle line received
– Overrun error detected
■ Transmitter clock output
■ Parity control:
– Transmits parity bit
– Checks parity of received data byte
■ Reduced power consumption mode
■ LIN Synch Break send capability
10.8.3 General Description
The interface is externally connected to another
Any SCI bidirectional communication requires a
minimum of two pins: Receive Data In (RDI) and
Transmit Data Out (TDO):
– SCLK: Transmitter clock output. This pin outputs
the transmitter data clock for synchronous trans-
mission (no clock pulses on start bit and stop bit,
and a software option to send a clock pulse on
the last data bit). This can be used to control pe-
ripherals that have shift registers (e.g. LCD driv-
ers). The clock phase and polarity are software
programmable.
– TDO: Transmit Data Output. When the transmit-
ter is disabled, the output pin returns to its I/O
port configuration. When the transmitter is ena-
bled and nothing is to be transmitted, the TDO
pin is at high level.
– RDI: Receive Data Input is the serial data input.
Oversampling techniques are used for data re-
covery by discriminating between valid incoming
data and noise.
Through these pins, serial data is transmitted and
received as frames comprising:
– An Idle Line prior to transmission or reception
– A start bit
– A data word (8 or 9 bits) least significant bit first
– A Stop bit indicating that the frame is complete.
This interface uses two types of baud rate generator:
– A conventional type for commonly-used baud
rates,
– An extended type with a prescaler offering a very
wide range of baud rates even with non-standard
oscillator frequencies.