Datasheet

 1997-2013 Microchip Technology Inc. DS30234E-page 105
PIC16C6X
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 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-
Applicable Devices
61 62 62A R6263R6364 64A R64 65 65A R65 66 67
minals and personal computers, or it can be configured
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.
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 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.
FIGURE 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 R = Readable bit
W = Writable bit
U = Unimplemented bit,
read as ‘0’
- n =Value at POR reset
bit7 bit0
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: TX9: 9-bit Transmit Enable bit
1 = Selects 9-bit transmission
0 = Selects 8-bit transmission
bit 5: 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: Unimplemented: Read as '0'
bit 2: BRGH: High Baud Rate Select bit
Asynchronous mode
1 = High speed
Note: For the PIC16C63/R63/65/65A/R65 the asynchronous high speed mode (BRGH = 1) may
experience a high rate of receive errors. It is recommended that BRGH = 0. If you desire a
higher baud rate than BRGH = 0 can support, refer to the device errata for additional infor-
mation or use the PIC16C66/67.
0 = Low speed
Synchronous mode
Unused in this mode
bit 1: TRMT: Transmit Shift Register Status bit
1 = TSR empty
0 = TSR full
bit 0: TX9D: 9th bit of transmit data. Can be parity bit.