PIC17C7XX_13 Datasheet, PDF (117/306 Pages) Microchip Technology – High-Performance 8-bit CMOS EPROM Microcontrollers with 10-bit A/D

14.0 UNIVERSAL SYNCHRONOUS
ASYNCHRONOUS RECEIVER
TRANSMITTER (USART)
MODULES
Each USART module is a serial I/O module. There are
two USART modules that are available on the
PIC17C7XX. They are specified as USART1 and
USART2. The description of the operation of these mod-
ules is generic in regard to the register names and pin
names used. Table 14-1 shows the generic names that
are used in the description of operation and the actual
names for both USART1 and USART2. Since the control
bits in each register have the same function, their names
are the same (there is no need to differentiate).
The Transmit Status and Control Register (TXSTA) is
shown in Figure 14-1, while the Receive Status and
Control Register (RCSTA) is shown in Figure 14-2.
PIC17C7XX
TABLE 14-1: USART MODULE GENERIC
NAMES
Generic Name USART1 Name USART2 Name
RCSTA
TXSTA
SPBRG
RCREG
TXREG
RCIE
RCIF
TXIE
TXIF
RX/DT
TX/CK
Registers
RCSTA1
RCSTA2
TXSTA1
TXSTA2
SPBRG1
SPBRG2
RCREG1
RCREG2
TXREG1
TXREG2
Interrupt Control Bits
RC1IE
RC2IE
RC1IF
RC2IF
TX1IE
TX2IE
TX1IF
TX2IF
Pins
RA4/RX1/DT1 RG6/RX2/DT2
RA5/TX1/CK1 RG7/TX2/CK2
REGISTER 14-1: TXSTA1 REGISTER (ADDRESS: 15h, BANK 0)
TXSTA2 REGISTER (ADDRESS: 15h, BANK 4)
R/W-0 R/W-0
R/W-0
R/W-0
U-0
CSRC
TX9
TXEN
SYNC
—
bit 7
U-0
R-1
R/W-x
—
TRMT TX9D
bit 0
bit 7
bit 6
bit 5
bit 4
bit 3-2
bit 1
bit 0
CSRC: Clock Source Select bit
Synchronous mode:
1 = Master mode (clock generated internally from BRG)
0 = Slave mode (clock from external source)
Asynchronous mode:
Don’t care
TX9: 9-bit Transmit Select bit
1 = Selects 9-bit transmission
0 = Selects 8-bit transmission
TXEN: Transmit Enable bit
1 = Transmit enabled
0 = Transmit disabled
SREN/CREN overrides TXEN in SYNC mode
SYNC: USART Mode Select bit
(Synchronous/Asynchronous)
1 = Synchronous mode
0 = Asynchronous mode
Unimplemented: Read as '0'
TRMT: Transmit Shift Register (TSR) Empty bit
1 = TSR empty
0 = TSR full
TX9D: 9th bit of Transmit Data (can be used to calculate the parity in software)
Legend:
R = Readable bit
- n = Value at POR Reset
W = Writable bit
’1’ = Bit is set
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared x = Bit is unknown
 1998-2013 Microchip Technology Inc.
DS30289C-page 117