PIC16F628-20P Datasheet, PDF (69/170 Pages) Microchip Technology – FLASH-Based 8-Bit CMOS Microcontroller

PIC16F62X
12.0 UNIVERSAL SYNCHRONOUS/
ASYNCHRONOUS RECEIVER/
TRANSMITTER (USART)
MODULE
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, or it can be config-
ured as a half duplex synchronous system that can
communicate with peripheral devices such as A/D or D/
A integrated circuits, Serial EEPROMs etc.
The USART can be configured in the following modes:
• Asynchronous (full duplex)
• Synchronous - Master (half duplex)
• Synchronous - Slave (half duplex)
Bit SPEN (RCSTA<7>), and bits TRISB<2:1>, have to
be set in order to configure pins RB2/TX/CK and RB1/
RX/DT as the Universal Synchronous Asynchronous
Receiver Transmitter.
REGISTER 12-1:
TXSTA: TRANSMIT STATUS AND CONTROL REGISTER (ADDRESS: 98h)
R/W-0
R/W-0
R/W-0
R/W-0
U-0
R/W-0
R-1
R/W-0
CSRC
TX9
TXEN
SYNC
—
BRGH
TRMT
TX9D
bit 7
bit 0
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
CSRC: Clock Source Select bit
Asynchronous mode
Don’t care
Synchronous mode
1 = Master mode (Clock generated internally from BRG)
0 = Slave mode (Clock from external source)
TX9: 9-bit Transmit Enable bit
1 = Selects 9-bit transmission
0 = Selects 8-bit transmission
TXEN: Transmit Enable bit⁽¹⁾
1 = Transmit enabled
0 = Transmit disabled
SYNC: USART Mode Select bit
1 = Synchronous mode
0 = Asynchronous mode
Unimplemented: Read as '0'
BRGH: High Baud Rate Select bit
Asynchronous mode
1 = High speed
0 = Low speed
Synchronous mode
Unused in this mode
TRMT: Transmit Shift Register STATUS bit
1 = TSR empty
0 = TSR full
TX9D: 9th bit of transmit data. Can be PARITY bit.
Note 1: SREN/CREN overrides TXEN in SYNC mode.
Legend:
R = Readable bit
W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR
’1’ = Bit is set
’0’ = Bit is cleared x = Bit is unknown
 2003 Microchip Technology Inc.
Preliminary
DS40300C-page 67