PIC16F688 Datasheet, PDF (89/174 Pages) Microchip Technology – 14-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

PIC16F688
FIGURE 10-2:
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
RC4/C2OUT/TX/CK pin
0
Pin Buffer
and Control
TRMT
SPEN
FIGURE 10-3:
ASYNCHRONOUS TRANSMISSION
Write to TXREG
BRG Output
(Shift Clock)
RC4/C2OUT/TX/CK
pin
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
Word 1
Start bit
bit 0
1 TCY
bit 1
Word 1
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1
Transmit Shift Reg
bit 7/8 _{Stop bit}
FIGURE 10-4:
Write to TXREG
BRG Output
(Shift Clock)
RC4/C2OUT/TX/CK
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
Word 1
Transmit Shift Reg.
bit 0
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.
 2004 Microchip Technology Inc.
Preliminary
DS41203B-page 87