Datasheet

Table Of Contents
© 2007 Microchip Technology Inc. DS39605F-page 141
PIC18F1220/1320
To set up an Asynchronous Transmission:
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRGH
and BRG16 bits, as required, to achieve the
desired baud rate.
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 16-2: EUSART TRANSMIT BLOCK DIAGRAM
FIGURE 16-3: ASYNCHRONOUS TRANSMISSION
TXIF
TXIE
Interrupt
TXEN
Baud Rate CLK
SPBRG
Baud Rate Generator
TX9D
MSb
LSb
Data Bus
TXREG Register
TSR Register
(8)
0
TX9
TRMT
SPEN
RB1/AN5/TX/CK/INT1 pin
Pin Buffer
and Control
8
• •
SPBRGH
BRG16
Word 1
Word 1
Transmit Shift Reg
Start bit bit 0 bit 1 bit 7/8
Write to TXREG
Word 1
BRG Output
(Shift Clock)
RB1/AN5/TX/
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
1 TCY
CK/INT1 (pin)
Stop bit