2003 Microchip Technology Inc.
DS39582B-page 125
PIC16F87XA
TABLE 10-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
10.4.2
USART SYNCHRONOUS SLAVE
RECEPTION
The operation of the Synchronous Master and Slave
modes is identical, except in the case of the Sleep
mode. Bit SREN is a “don't care” in Slave mode.
If receive is enabled by setting bit CREN prior to the
SLEEP
instruction, then a word may be received during
Sleep. On completely receiving the word, the RSR reg-
ister will transfer the data to the RCREG register and if
enable bit RCIE bit is set, the interrupt generated will
wake the chip from Sleep. If the global interrupt is
enabled, the program will branch to the interrupt vector
(0004h).
When setting up a Synchronous Slave Reception,
follow these steps:
1.
Enable the synchronous master serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
2.
If interrupts are desired, set enable bit RCIE.
3.
If 9-bit reception is desired, set bit RX9.
4.
To enable reception, set enable bit CREN.
5.
Flag bit RCIF will be set when reception is
complete and an interrupt will be generated if
enable bit RCIE was set.
6.
Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
7.
Read the 8-bit received data by reading the
RCREG register.
8.
If any error occurred, clear the error by clearing
bit CREN.
9.
If using interrupts, ensure that GIE and PEIE
(bits 7 and 6) of the INTCON register are set.
TABLE 10-11: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE 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
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
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, read as ‘
0
’. Shaded cells are not used for synchronous slave transmission.
Note
1:
Bits PSPIE and PSPIF are reserved on 28-pin devices; always maintain these bits clear.
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, read as ‘
0
’. Shaded cells are not used for synchronous slave reception.
Note
1:
Bits PSPIE and PSPIF are reserved on 28-pin devices, always maintain these bits clear.
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