PIC18F4539 Datasheet, PDF (175/322 Pages) Microchip Technology – Enhanced FLASH Microcontrollers with Single Phase Induction Motor Control Kernel

FIGURE 17-2:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX/CK (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
PIC18FXX39
bit 7/8 _{STOP bit}
FIGURE 17-3:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX/CK (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.
Word 2
Transmit Shift Reg.
Note: This timing diagram shows two consecutive transmissions.
TABLE 17-6: 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 000x 0000 000u
PIR1
PSPIF⁽¹⁾ ADIF
RCIF TXIF SSPIF
— _{TMR2IF TMR1IF 0000 0000 0000 0000}
PIE1
PSPIE⁽¹⁾ ADIE
RCIE TXIE SSPIE
— _{TMR2IE TMR1IE 0000 0000 0000 0000}
IPR1
PSPIP⁽¹⁾ ADIP
RCIP TXIP SSPIP
— _{TMR2IP TMR1IP 0000 0000 0000 0000}
RCSTA SPEN
RX9 SREN CREN ADDEN FERR OERR RX9D 0000 -00x 0000 -00x
TXREG USART Transmit Register
0000 0000 0000 0000
TXSTA CSRC
TX9
TXEN SYNC — BRGH TRMT TX9D 0000 -010 0000 -010
SPBRG 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: The PSPIF, PSPIE and PSPIP bits are reserved on the PIC18F2X39 devices; always maintain these bits
clear.
 2002 Microchip Technology Inc.
Preliminary
DS30485A-page 173