PIC18F2331 Datasheet, PDF (233/396 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High Performance PWM and A/D

PIC18F2331/2431/4331/4431
FIGURE 19-2:
USART TRANSMIT BLOCK DIAGRAM
TXIE
TXIF
MSb
(8)
Interrupt
TXEN Baud Rate CLK
Data Bus
TXREG Register
8
•••
TSR Register
BRG16
SPBRGH SPBRG
Baud Rate Generator
TX9
TX9D
LSb
RC6/TX/CK/SS pin
0
Pin Buffer
and Control
TRMT
SPEN
FIGURE 19-3:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX/CK/SS
(pin)
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION
Word 1
Start bit
bit 0
1 TCY
bit 1
Word 1
Word 1
Transmit Shift Reg
bit 7/8 _{Stop bit}
FIGURE 19-4:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX/CK/SS
(pin)
TXIF bit
(Interrupt Reg. Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION (BACK TO BACK)
Word 1
Word 2
1 TCY
Start bit
bit 0
Word 1
Transmit Shift Reg.
1 TCY
bit 1
Word 1
bit 7/8 Stop bit
Start bit
bit 0
Word 2
Word 2
Transmit Shift Reg.
Note: This timing diagram shows two consecutive transmissions.
 2003 Microchip Technology Inc.
Preliminary
DS39616B-page 231