Enhanced SCI Module Overview
983
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Serial Communications Interface (SCI)
•
A programmable baud generator
•
Data-memory-mapped control and status registers
The SCI receiver and transmitter can operate either independently or simultaneously.
13.1.1.1 SCI Module Signal Summary
Table 13-3. SCI Module Signal Summary
Signal Name
Description
External signals
SCIRXD
SCI Asynchronous Serial Port receive data
SCITXD
SCI Asynchronous Serial Port transmit data
Control
Baud clock
LSPCLK Prescaled clock
Interrupt signals
TXINT
Transmit interrupt
RXINT
Receive Interrupt
13.1.1.2 Multiprocessor and Asynchronous Communication Modes
The SCI has two multiprocessor protocols, the idle-line multiprocessor mode (see
) and
the address-bit multiprocessor mode (see
). These protocols allow efficient data transfer
between multiple processors.
The SCI offers the universal asynchronous receiver/transmitter (UART) communications mode for
interfacing with many popular peripherals. The asynchronous mode (see
) requires two
lines to interface with many standard devices such as terminals and printers that use RS-232-C formats.
Data transmission characteristics include:
•
One start bit
•
One to eight data bits
•
An even/odd parity bit or no parity bit
•
One or two stop bits
13.1.1.3 SCI Programmable Data Format
SCI data, both receive and transmit, is in NRZ (non-return-to-zero) format. The NRZ data format, shown in
, consists of:
•
One start bit
•
One to eight data bits
•
An even/odd parity bit (optional)
•
One or two stop bits
•
An extra bit to distinguish addresses from data (address-bit mode only)
The basic unit of data is called a character and is one to eight bits in length. Each character of data is
formatted with a start bit, one or two stop bits, and optional parity and address bits. A character of data
with its formatting information is called a frame and is shown in