PIC18F2331 Datasheet, PDF (236/396 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High Performance PWM and A/D

PIC18F2331/2431/4331/4431
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 19.2 “USART 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 19-6:
RX (pin)
Rcv Shift
Reg
Rcv Buffer Reg
Read Rcv
Buffer Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
ASYNCHRONOUS RECEPTION
Start
bit _{bit0 bit1}
Start
bit7/8 Stop bit bit0
bit
Word 1
RCREG
Start
bit7/8 Stop bit
bit
Word 2
RCREG
bit7/8 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 19-6: 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
PIR1
PIE1
IPR1
GIE/GIEH
—
—
—
PEIE/GIEL
ADIF
ADIE
ADIP
TMR0IE
RCIF
RCIE
RCIP
INT0IE
TXIF
TXIE
TXIP
RBIE
—
—
—
TMR0IF INT0IF RBIF
CCP1IF TMR2IF TMR1IF
CCP1IE TMR2IE TMR1IE
CCP1IP TMR2IP TMR1IP
0000 000x
-000 -000
-000 -000
-111 -111
0000 000u
-000 -000
-000 -000
-111 -111
RCSTA
SPEN
RX9
SREN CREN ADDEN FERR OERR RX9D _{0000 -00x 0000 -00x}
RCREG USART 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.
DS39616B-page 234
Preliminary
 2003 Microchip Technology Inc.