Datasheet

PIC17C7XX
DS30289C-page 118  1998-2013 Microchip Technology Inc.
The USART can be configured as a full duplex asyn-
chronous system that can communicate with peripheral
devices such as CRT terminals and personal comput-
ers, or it can be configured as a half duplex synchro-
nous 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)
The SPEN (RCSTA<7>) bit has to be set in order to
configure the I/O pins as the Serial Communication
Interface (USART).
The USART module will control the direction of the RX/
DT and TX/CK pins, depending on the states of the
USART configuration bits in the RCSTA and TXSTA
registers. The bits that control I/O direction are:
• SPEN
• TXEN
•SREN
• CREN
•CSRC
REGISTER 14-2: RCSTA1 REGISTER (ADDRESS: 13h, BANK 0)
RCSTA2 REGISTER (ADDRESS: 13h, BANK 4)
R/W-0 R/W-0 R/W-0 R/W-0 U-0 R-0 R-0 R-x
SPEN RX9 SREN CREN
— FERR OERR RX9D
bit 7 bit 0
bit 7 SPEN: Serial Port Enable bit
1 = Configures TX/CK and RX/DT pins as serial port pins
0 = Serial port disabled
bit 6 RX9: 9-bit Receive Select bit
1 = Selects 9-bit reception
0 = Selects 8-bit reception
bit 5 SREN: Single Receive Enable bit
This bit enables the reception of a single byte. After receiving the byte, this bit is automatically
cleared.
Synchronous mode:
1 = Enable reception
0 = Disable reception
Note: This bit is ignored in synchronous slave reception.
Asynchronous mode:
Don’t care
bit 4 CREN: Continuous Receive Enable bit
This bit enables the continuous reception of serial data.
Asynchronous mode:
1 = Enable continuous reception
0 = Disables continuous reception
Synchronous mode:
1 = Enables continuous reception until CREN is cleared (CREN overrides SREN)
0 = Disables continuous reception
bit 3 Unimplemented: Read as '0'
bit 2 FERR: Framing Error bit
1 = Framing error (updated by reading RCREG)
0 = No framing error
bit 1 bit OERR: Overrun Error bit
1 = Overrun (cleared by clearing CREN)
0 = No overrun error
bit 0 RX9D: 9th bit of Receive Data (can be the software calculated parity bit)
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
- n = Value at POR Reset ’1’ = Bit is set ’0’ = Bit is cleared x = Bit is unknown