PIC18F2450/4450
2006 Microchip Technology Inc.
Advance Information
DS39760A-page 153
15.0
ENHANCED UNIVERSAL
SYNCHRONOUS RECEIVER
TRANSMITTER (EUSART)
The Universal Synchronous Asynchronous Receiver
Transmitter (USART) module is one of the two serial
I/O modules. (USART is also known as a Serial
Communications Interface or SCI.) The USART can be
configured as a full-duplex asynchronous system that
can communicate with peripheral devices, such as
CRT terminals and personal computers. It can also be
configured as a half-duplex synchronous system that
can communicate with peripheral devices, such as A/D
or D/A integrated circuits, serial EEPROMs and so on.
The
Enhanced
Universal
Synchronous
Receiver
Transmitter (EUSART) module implements additional
features, including Automatic Baud Rate Detection
(ABD) and calibration, automatic wake-up on Sync
Break reception and 12-bit Break character transmit.
These features make it ideally suited for use in Local
Interconnect Network bus (LIN bus) systems.
The EUSART can be configured in the following
modes:
Asynchronous (full-duplex) with:
- Auto-wake-up on character reception
- Auto-baud calibration
- 12-bit Break character transmission
Synchronous – Master (half-duplex) with
selectable clock polarity
Synchronous – Slave (half-duplex) with selectable
clock polarity
The pins of the Enhanced USART are multiplexed with
PORTC. In order to configure RC6/TX/CK and RC7/RX/
DT as an EUSART:
bit SPEN (RCSTA<7>) must be set (= 1)
bit TRISC<7> must be set (= 1)
bit TRISC<6> must be cleared (= 0) for
Asynchronous and Synchronous Master modes
or set (= 1) for Synchronous Slave mode
The operation of the Enhanced USART module is
controlled through three registers:
Transmit Status and Control (TXSTA)
Receive Status and Control (RCSTA)
Baud Rate Control (BAUDCON)
These are detailed on the following pages in
and
respectively.
Note:
The EUSART control will automatically
reconfigure the pin from input to output as
needed.
