PIC16C63A/65B/73B/74B
as a half duplex synchronous system that can commu-
nicate with peripheral devices, such as A/D or D/A inte-
grated circuits, Serial EEPROMs etc.
11.0 ADDRESSABLE UNIVERSAL
SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (USART)
The USART can be configured in the following modes:
• Asynchronous (full duplex)
The Universal Synchronous Asynchronous Receiver
Transmitter (USART) module is one of the two serial
I/O modules. (USART is also known as a Serial Com-
munications Interface or SCI.) The USART can be con-
figured as a full duplex asynchronous system that can
communicate with peripheral devices, such as CRT ter-
minals and personal computers, or it can be configured
• Synchronous - Master (half duplex)
• Synchronous - Slave (half duplex)
Bits SPEN (RCSTA<7>) and TRISC<7:6> have to be
set in order to configure pins RC6/TX/CK and
RC7/RX/DT as the universal synchronous asynchro-
nous receiver transmitter.
REGISTER 11-1: TXSTA: TRANSMIT STATUS AND CONTROL REGISTER (ADDRESS 98h)
R/W-0
CSRC
R/W-0
TX9
R/W-0
TXEN
R/W-0
SYNC
U-0
R/W-0
BRGH
R-1
R/W-0
TX9D
—
TRMT
bit 7
bit 0
bit 7
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)
bit 6
bit 5
TX9: 9-bit Transmit Enable bit
1= Selects 9-bit transmission
0= Selects 8-bit transmission
TXEN: Transmit Enable bit
1= Transmit enabled
0= Transmit disabled
Note: SREN/CREN overrides TXEN in SYNC mode.
bit 4
SYNC: USART Mode Select bit
1= Synchronous mode
0= Asynchronous mode
bit 3
bit 2
Unimplemented: Read as '0'
BRGH: High Baud Rate Select bit
Asynchronous mode:
1= High speed
0= Low speed
Synchronous mode:
Unused in this mode
bit 1
bit 0
TRMT: Transmit Shift Register Status bit
1= TSR empty
0= TSR full
TX9D: 9th bit of Transmit Data. Can be parity bit.
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared x = Bit is unknown
’1’ = Bit is set
2000 Microchip Technology Inc.
DS30605C-page 65
MICROCHIP [ MICROCHIP ]
