PIC16F87XA
DS39582B-page 120
2003 Microchip Technology Inc.
FIGURE 10-7:
ASYNCHRONOUS RECEPTION WITH ADDRESS DETECT
FIGURE 10-8:
ASYNCHRONOUS RECEPTION WITH ADDRESS BYTE FIRST
TABLE 10-7:
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Start
bit
bit 1
bit 0
bit 8
bit 0
Stop
bit
Start
bit
bit 8
Stop
bit
RC7/RX/DT
Load RSR
Read
RCIF
Word 1
RCREG
Bit 8 =
0
, Data Byte
Bit 8 =
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
.
(pin)
Start
bit
bit 1
bit 0
bit 8
bit 0
Stop
bit
Start
bit
bit 8
Stop
bit
RC7/RX/DT
Load RSR
Read
RCIF
Word 1
RCREG
Bit 8 =
1
, Address Byte
Bit 8 =
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
.
(pin)
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
TMR0IE
INTE
RBIE
TMR0IF
INTF
R0IF
0000 000x
0000 000u
0Ch
PIR1
PSPIF
(1)
ADIF
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF TMR1IF
0000 0000
0000 0000
18h
RCSTA
SPEN
RX9
SREN
CREN ADDEN
FERR
OERR
RX9D
0000 000x
0000 000x
1Ah
RCREG
USART Receive 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 reception.
Note
1:
Bits PSPIE and PSPIF are reserved on 28-pin devices; always maintain these bits clear.
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