SFR explanation for PIC16F873(15)

RCSTA ( Receive Status and Control Register ) 18h

This register controls USART receive function.

The value in the parenthesis is in the condition immediately after the turning on.

SPEN : Serial Port Enable bit

	1	:	Serial port enabled ( Configures RC7/RX/DT and RC6/TX/CK pins as serial port pins )
	0	:	Serial port disacled

RX9 : 9-bit Receive Enable bit

	1	:	Selects 9-bit reception
	0	:	Selects 8-bit reception

SREN : Single Receive Enable bit

Asynchronous mode

Don't care

Synchronous mode - master

	1	:	Enables single receive
	0	:	Disables single receive

This bit is cleared after reception ic complete.

Synchronous mode - slave

Unused in this mode

CREN : Continuous Receive Enable bit

Asynchronous mode

	1	:	Enables continuous receive
	0	:	Disables continuous receive

Synchronous mode

	1	:	Enables continuous receive until enable bit CREN is cleared ( CREN is overrides SREN )
	0	:	Disables continuous receive

ADDEN : Address Detect Enable bit

Asynchronous mode 9-bit ( RX9 = 1 )

	1	:	Enables address detection enable interrupt and load of the receive buffer when RSR<8> is set
	0	:	Disables address detection all bytes are receive, and ninth bit can be used as parity bit

FERR : Framing Error bit ( Read only )

	1	:	Framing error ( Can be updated by reading RCREG register and receive next valid byte )
	0	:	No framing error

OERR : Overrun Error bit ( Read only )

	1	:	Overrun error ( Can be cleared by clearing bit CREN )
	0	:	No overrun error

RX9D : 9th bit of receive data ( Read only )

TXREG ( Transmit buffer ) 19h

Transmit data is set to this buffer.

RCREG ( Receive buffer ) 1Ah

Received data is stored to this buffer.