PIC18FXX20 Datasheet, PDF (207/366 Pages) Microchip Technology – 64/80-Pin High Performance 1 Mbit Enhanced FLASH Microcontrollers with A/D

FIGURE 18-2:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX1/CK1 (pin)
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION
Word 1
START bit
bit 0
bit 1
Word 1
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1
Transmit Shift Reg
PIC18FXX20
bit 7/8 _{STOP bit}
FIGURE 18-3:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX1/CK1 (pin)
TXIF bit
(Interrupt Reg. Flag)
ASYNCHRONOUS TRANSMISSION (BACK TO BACK)
Word 1
Word 2
START bit
bit 0
bit 1
Word 1
bit 7/8 STOP bit ^{START bit}
bit 0
Word 2
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1
Transmit Shift Reg.
Note: This timing diagram shows two consecutive transmissions.
Word 2
Transmit Shift Reg.
TABLE 18-6: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Name
Bit 7
Bit 6
Bit 5 Bit 4 Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR,
BOR
Value on
all other
RESETS
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 0000 0000 0000
PIR1
PSPIF
ADIF
RC1IF TX1IF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000
PIE1
PSPIE
ADIE
RC1IE TX1IE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000
IPR1
PSPIP
ADIP
RC1IP TX1IP SSPIP CCP1IP TMR2IP TMR1IP 0111 1111 0111 1111
PIR3
—
—
RC2IF TX2IF TMR4IF CCP5IF CCP4IF CCP3IF --00 0000 --00 0000
PIE3
—
—
RC2IE TX2IE TMR4IE CCP5IE CCP4IE CCP3IE --00 0000 --00 0000
IPR3
—
—
RC2IP TX2IP TMR4IP CCP5IP CCP4IP CCP3IP --11 1111 --11 1111
RCSTAx⁽¹⁾ SPEN
RX9
SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
TXREGx⁽¹⁾ USART Transmit Register
0000 0000 0000 0000
TXSTAx⁽¹⁾ CSRC
TX9
TXEN SYNC
—
BRGH TRMT TX9D 0000 -010 0000 -010
SPBRGx⁽¹⁾ Baud Rate Generator Register
0000 0000 0000 0000
Legend: x = unknown, - = unimplemented locations read as '0'. Shaded cells are not used for Asynchronous Transmission.
Note 1: Register names generically refer to both of the identically named registers for the two USART modules, where ‘x’
indicates the particular module. Bit names and RESET values are identical between modules.
 2003 Microchip Technology Inc.
Advance Information
DS39609A-page 205