
2003 Microchip Technology Inc.
DS30569B-page 71
PIC16F870/871
FIGURE 9-7:
ASYNCHRONOUS RECEPTION WITH ADDRESS DETECT
FIGURE 9-8:
ASYNCHRONOUS RECEPTION WITH ADDRESS BYTE FIRST
TABLE 9-7:
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
START
bit
bit1
bit0
bit8
bit0
STOP
bit
START
bit
bit8
STOP
bit
RC7/RX/DT (pin)
Load RSR
Read
RCIF
Word 1
RCREG
Bit8 = 0, Data Byte
Bit8 = 1, Address Byte
Note:
This timing diagram shows a data byte followed by an address byte. The data byte is not read into the RCREG (receive buffer)
because ADDEN = 1.
START
bit
bit1
bit0
bit8
bit0
STOP
bit
START
bit
bit8
STOP
bit
RC7/RX/DT (pin)
Load RSR
Read
RCIF
Word 1
RCREG
Bit8 = 1, Address Byte
Bit8 = 0, Data Byte
Note:
This timing diagram shows a data byte followed by an address byte. The data byte is not read into the RCREG (receive buffer)
because ADDEN was not updated and still = 0.
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 0000 -000
0000 -000
18h
RCSTA
SPEN
RX9
SREN
CREN ADDEN
FERR
OERR
RX9D
0000 000x
1Ah
RCREG
USART Receive Register
0000 0000
8Ch
PIE1
PSPIE(1)
ADIE
RCIE
TXIE
—
CCP1IE TMR2IE TMR1IE 0000 -000
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.