PIC16C7X Datasheet, PDF (107/288 Pages) Microchip Technology – 8-Bit CMOS Microcontrollers with A/D Converter

PIC16C7X
Steps to follow when setting 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 12.1)
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 trans-
mission).
FIGURE 12-8: ASYNCHRONOUS MASTER TRANSMISSION
Write to TXREG
BRG output
(shift clock)
RC6/TX/CK (pin)
TXIF bit
(Transmit buffer
reg. empty flag)
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 12-9: 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 12-6: 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
0Ch
PIR1
PSPIF⁽¹⁾ ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF ^{0000 0000 0000 0000}
18h
RCSTA SPEN RX9 SREN CREN — FERR OERR RX9D ^{0000 -00x 0000 -00x}
19h
TXREG USART Transmit 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 the PIC16C73/73A/76, always maintain these bits clear.
© 1997 Microchip Technology Inc.
DS30390E-page 107