
2003 Microchip Technology Inc.
DS30569B-page 69
PIC16F870/871
When setting up an Asynchronous Reception, follow
these steps:
1.
Initialize the SPBRG register for the appropriate
baud rate. If a high speed baud rate is desired,
2.
Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
3.
If interrupts are desired, then set enable bit
RCIE.
4.
If 9-bit reception is desired, then set bit RX9.
5.
Enable the reception by setting bit CREN.
6.
Flag bit RCIF will be set when reception is com-
plete and an interrupt will be generated if enable
bit RCIE is set.
7.
Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
8.
Read the 8-bit received data by reading the
RCREG register.
9.
If any error occurred, clear the error by clearing
enable bit CREN.
10. If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
TABLE 9-6:
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
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,
10Bh,18Bh
INTCON
GIE
PEIE
T0IE
INTE
RBIE
T0IF
INTF
R0IF
0000 000x
0000 000u
0Ch
PIR1
PSPIF(1)
ADIF
RCIF
TXIF
—
CCP1IF
TMR2IF
TMR1IF
-000 0000
18h
RCSTA
SPEN
RX9
SREN
CREN
—
FERR
OERR
RX9D
0000 -00x
1Ah
RCREG USART Receive Register
0000 0000
8Ch
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
—
CCP1IE
TMR2IE TMR1IE
0000 -000
98h
TXSTA
CSRC
TX9
TXEN
SYNC
—BRGH
TRMT
TX9D
0000 -010
99h
SPBRG
Baud Rate Generator Register
0000 0000
Legend:
x
= unknown, - = unimplemented locations read as '0'. Shaded cells are not used for asynchronous reception.
Note
1:
Bits PSPIE and PSPIF are reserved on the PIC16F870; always maintain these bits clear.