PIC18F2221_1 Datasheet, PDF (222/402 Pages) Microchip Technology – Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F2221/2321/4221/4321 FAMILY
FIGURE 19-3:
EUSART TRANSMIT BLOCK DIAGRAM
TXIE
TXIF
Interrupt
MSb
(8)
Data Bus
TXREG Register
8
LSb
•••
0
TSR Register
TXCKP
Pin Buffer
and Control
TXEN Baud Rate CLK
BRG16
SPBRGH SPBRG
Baud Rate Generator
TX9
TX9D
TRMT
SPEN
TX pin
FIGURE 19-4:
Write to TXREG
BRG Output
(Shift Clock)
TX (pin)
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION, TXCKP = 0 (TX NOT INVERTED)
Word 1
Start bit
bit 0
1 TCY
bit 1
Word 1
bit 7/8 _{Stop bit}
Word 1
Transmit Shift Reg
FIGURE 19-5:
ASYNCHRONOUS TRANSMISSION (BACK TO BACK),
TXCKP = 0 (TX NOT INVERTED)
Write to TXREG
BRG Output
(Shift Clock)
TX (pin)
TXIF bit
(Interrupt Reg. Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
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.
DS39689F-page 222
© 2009 Microchip Technology Inc.