 English |
|
|
|
|
|
|
|
| PIC18F2220_07 Datasheet, PDF (207/386 Pages) Microchip Technology – 28/40/44-Pin High-Performance, Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology | |||
| |||
| ◁ |
PIC18F2220/2320/4220/4320
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 (Section 18.2 âUSART Baud
Rate Generator (BRG)â).
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).
8. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
FIGURE 18-5:
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 18-7: 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
PSPIF(1)
PSPIE(1)
PSPIP(1)
PEIE/
GIEL
ADIF
ADIE
ADIP
TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x
RCIF
RCIE
RCIP
TXIF
TXIE
TXIP
SSPIF CCP1IF TMR2IF TMR1IF 0000 0000
SSPIE CCP1IE TMR2IE TMR1IE 0000 0000
SSPIP CCP1IP TMR2IP TMR1IP 1111 1111
0000 000u
0000 0000
0000 0000
1111 1111
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 â BRGH TRMT TX9D 0000 -010 0000 -010
SPBRG Baud Rate Generator Register
0000 0000 0000 0000
Legend: x = unknown, - = unimplemented locations read as â0â. Shaded cells are not used for asynchronous reception.
Note 1: The PSPIF, PSPIE and PSPIP bits are reserved on the PIC18F2X20 devices; always maintain these bits clear.
© 2007 Microchip Technology Inc.
DS39599F-page 205
|
▷ |
German
Russian
Spanish
Italian
Polish
Chinese
Japanese
Korean
French
Portuguese