Datasheet

© 2007 Microchip Technology Inc. DS39629C-page 207
PIC18F6390/6490/8390/8490
FIGURE 16-4: ASYNCHRONOUS TRANSMISSION
FIGURE 16-5: ASYNCHRONOUS TRANSMISSION (BACK-TO-BACK)
TABLE 16-5: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Word 1
Word 1
Transmit Shift Reg
Start bit bit 0 bit 1 bit 7/8
Write to TXREG1
BRG Output
(Shift Clock)
TX1 (pin)
TX1IF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
1 TCY
Word 1
Stop bit
Transmit Shift Reg.
Write to TXREG1
BRG Output
(Shift Clock)
TX1 (pin)
TX1IF bit
(Interrupt Reg. Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1
Word 2
Word 1
Word 2
Stop bit
Start bit
Transmit Shift Reg.
Word 1
Word 2
bit 0 bit 1
bit 7/8 bit 0
Note: This timing diagram shows two consecutive transmissions.
1 TCY
1 TCY
Start bit
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset
Values
on Page
INTCON GIE/GIEH PEIE/GIEL
TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 59
PIR1 — ADIF RC1IF TX1IF SSPIF CCP1IF TMR2IF TMR1IF 61
PIE1
— ADIE RC1IE TX1IE SSPIE CCP1IE TMR2IE TMR1IE 61
IPR1
— ADIP RC1IP TX1IP SSPIP CCP1IP TMR2IP TMR1IP 61
RCSTA1 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 61
TXREG1
EUSART1 Transmit Register 61
TXSTA1
CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 61
BAUDCON1 ABDOVF RCIDL — SCKP BRG16 — WUE ABDEN 62
SPBRGH1 EUSART1 Baud Rate Generator Register High Byte 62
SPBRG1 EUSART1 Baud Rate Generator Register Low Byte 61
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmission.