PIC16F631/677/685/687/689/690
The EUSART module includes the following capabilities:
12.0 ENHANCED UNIVERSAL
• Full-duplex asynchronous transmit and receive
• Two-character input buffer
SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (EUSART)
• One-character output buffer
• Programmable 8-bit or 9-bit character length
• Address detection in 9-bit mode
The Enhanced Universal Synchronous Asynchronous
Receiver Transmitter (EUSART) module is a serial I/O
communications peripheral. It contains all the clock
generators, shift registers and data buffers necessary
to perform an input or output serial data transfer
independent of device program execution. The
EUSART, also known as a Serial Communications
Interface (SCI), can be configured as a full-duplex
asynchronous system or half-duplex synchronous
• Input buffer overrun error detection
• Received character framing error detection
• Half-duplex synchronous master
• Half-duplex synchronous slave
• Programmable clock polarity in synchronous
modes
The EUSART module implements the following
additional features, making it ideally suited for use in
Local Interconnect Network (LIN) bus systems:
system.
Full-Duplex
mode
is
useful
for
communications with peripheral systems, such as CRT
terminals and personal computers. Half-Duplex
Synchronous mode is intended for communications
with peripheral devices, such as A/D or D/A integrated
circuits, serial EEPROMs or other microcontrollers.
These devices typically do not have internal clocks for
baud rate generation and require the external clock
signal provided by a master synchronous device.
• Automatic detection and calibration of the baud rate
• Wake-up on Break reception
• 13-bit Break character transmit
Block diagrams of the EUSART transmitter and
receiver are shown in Figure 12-1 and Figure 12-2.
FIGURE 12-1:
EUSART TRANSMIT BLOCK DIAGRAM
Data Bus
TXIE
Interrupt
TXIF
TXREG Register
8
TX/CK pin
MSb
(8)
LSb
0
Pin Buffer
and Control
• • •
Transmit Shift Register (TSR)
TXEN
TRMT
SPEN
Baud Rate Generator
BRG16
FOSC
÷ n
TX9
n
+ 1
Multiplier x4
x16 x64
TX9D
SYNC
BRGH
BRG16
1
X
X
X
1
1
0
1
0
0
0
1
0
0
0
SPBRGH
SPBRG
© 2007 Microchip Technology Inc.
DS41262D-page 149
MICROCHIP [ MICROCHIP ]
