PIC16F737-I Datasheet, PDF (141/276 Pages) Microchip Technology – 28/40/44-Pin, 8-Bit CMOS Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC16F7X7
When setting up an Asynchronous Transmission,
follow these steps:
1. Initialize the SPBRG register for the appropriate
baud rate. If a high-speed baud rate is desired,
set bit BRGH (see Section 11.1 “AUSART
Baud Rate Generator (BRG)”).
2. Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
3. If interrupts are desired, then set enable bit TXIE.
4. If 9-bit transmission is desired, then set transmit
bit TX9.
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 GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
FIGURE 11-2:
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX/CK (pin)
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
ASYNCHRONOUS MASTER TRANSMISSION
Word 1
Start bit
bit 0
bit 1
Word 1
bit 7/8 Stop bit
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1
Transmit Shift Reg
FIGURE 11-3:
ASYNCHRONOUS MASTER TRANSMISSION (BACK TO BACK)
Write to TXREG
BRG Output
(Shift Clock)
RC6/TX/CK (pin)
TXIF bit
(Interrupt Reg. Flag)
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 11-7: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Address 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
0Bh, 8Bh, INTCON GIE
10Bh,18Bh
0Ch
PIR1
PSPIF⁽¹⁾
PEIE
ADIF
TMR0IE INT0IE
RCIF TXIF
RBIE
SSPIF
TMR0IF INT0IF
CCP1IF TMR2IF
RBIF
TMR1IF
0000 000x
0000 0000
0000 000u
0000 0000
18h
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
19h
TXREG AUSART Transmit Data Register
0000 0000 0000 0000
8Ch
PIE1
PSPIE⁽¹⁾ ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000
98h
TXSTA CSRC TX9 TXEN SYNC — BRGH TRMT TX9D 0000 -010 0000 -010
99h
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: Bits PSPIE and PSPIF are reserved on 28-pin devices; always maintain these bits clear.
 2004 Microchip Technology Inc.
DS30498C-page 139