
PIC18FXX39
DS30485A-page 166
Preliminary
2002 Microchip Technology Inc.
REGISTER 17-1:
TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
R/W-0
U-0
R/W-0
R-1
R/W-0
CSRC
TX9
TXEN
SYNC
—BRGH
TRMT
TX9D
bit 7
bit 0
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
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 Address/Data bit or a parity bit
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown