PIC18F1220_07 Datasheet, PDF (146/308 Pages) Microchip Technology – 18/20/28-Pin High-Performance, Enhanced Flash Microcontrollers with 10-bit A/D and nanoWatt Technology

PIC18F1220/1320
To set up an Asynchronous Transmission:
1. Initialize the SPBRG register for the appropriate
baud rate. If a high-speed baud rate is desired,
set bit BRGH (see Section 16.2 “EUSART
Baud Rate Generator (BRG)”).
2. Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
3. If interrupts are desired, set enable bit TXIE.
4. If 9-bit transmission is desired, set transmit bit
TX9. Can be used as address/data bit.
5. Enable the transmission by setting bit TXEN,
which will also set bit TXIF.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. Load data to the TXREG register (starts
transmission).
If using interrupts, ensure that the GIE and PEIE bits in
the INTCON register (INTCON<7:6>) are set.
FIGURE 16-6:
RX (pin)
Rcv Shift
Reg
Rcv Buffer Reg
Read Rcv
Buffer Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
ASYNCHRONOUS RECEPTION
Start
bit bit 0 bit 1
Start
bit 7/8 Stop bit bit 0
bit
Word 1
RCREG
Start
bit 7/8 Stop bit
bit
Word 2
RCREG
bit 7/8 Stop
bit
Note:
This timing diagram shows three words appearing on the RX input. The RCREG (receive buffer) is read after
the third word, causing the OERR (overrun) bit to be set.
TABLE 16-6: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
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
—
ADIF
RCIF TXIF
— CCP1IF TMR2IF TMR1IF -000 -000 -000 -000
PIE1
—
ADIE
RCIE TXIE
— CCP1IE TMR2IE TMR1IE -000 -000 -000 -000
IPR1
—
ADIP
RCIP TXIP
— CCP1IP TMR2IP TMR1IP -111 -111 -111 -111
RCSTA
SPEN
RX9
SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
RCREG EUSART Receive Register
0000 0000 0000 0000
TXSTA
CSRC
TX9
TXEN SYNC SENDB BRGH TRMT TX9D 0000 0010 0000 0010
BAUDCTL
—
RCIDL
—
SCKP BRG16 —
WUE ABDEN -1-1 0-00 -1-1 0-00
SPBRGH Baud Rate Generator Register High Byte
0000 0000 0000 0000
SPBRG Baud Rate Generator Register Low Byte
0000 0000 0000 0000
Legend: x = unknown, – = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
DS39605F-page 144
© 2007 Microchip Technology Inc.