SFR explanation for PIC16F873(16)

TXSTA ( Transmit Status and Control Register ) 98h

This register controls USART transmit function.

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

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 )

TX9 : 9-bit Transmit Enable bit

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

TXEN : Transmit Enable bit

	1	:	Transmit enable
	0	:	Transmit disable

SREN/CREN of RCSTA register overrides TXEN in SYNC mode

SYNC : USART Mode Select bit

	1	:	Synchronous mode
	0	:	Asynchronous mode

BRGH : High Baud Rate Select bit

Asynchronous mode

	1	:	High speed
	0	:	Low speed

Synchronous mode

Unused in this mode

TRMT : Transmit Shift Register Status bit ( Read only )

	1	:	TSR empty
	0	:	TSR full

TX9D : 9th bit of transmit data. Can be parity bit.