
PIC18F2480/2580/4480/4580
DS39637A-page 246
Preliminary
2004 Microchip Technology Inc.
18.4.2
EUSART SYNCHRONOUS SLAVE
RECEPTION
The operation of the Synchronous Master and Slave
modes is identical, except in the case of Sleep or any
Idle mode and bit SREN, which is a “don’t care” in
Slave mode.
If receive is enabled by setting the CREN bit prior to
entering Sleep or any Idle mode, then a word may be
received while in this low-power mode. Once the word
is received, the RSR register will transfer the data to the
RCREG register; if the RCIE enable bit is set, the inter-
rupt generated will wake the chip from the low-power
mode. If the global interrupt is enabled, the program will
branch to the interrupt vector.
To set up a Synchronous Slave Reception:
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. An interrupt will be generated if
enable bit RCIE was set.
6.
Read the RCSTA register to get the 9th 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 the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
TABLE 18-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON
PIR1
PIE1
IPR1
RCSTA
RCREG
TXSTA
BAUDCON
SPBRGH
SPBRG
Legend:
Note 1:
GIE/GIEH PEIE/GIEL
PSPIF
(1)
PSPIE
(1)
PSPIP
(1)
SPEN
EUSART Receive Register
CSRC
ABDOVF
EUSART Baud Rate Generator Register High Byte
EUSART Baud Rate Generator Register Low Byte
— = unimplemented, read as ‘
0
’. Shaded cells are not used for synchronous slave reception.
Reserved in PIC18F2X80 devices; always maintain these bits clear.
TMR0IE
RCIF
RCIE
RCIP
SREN
INT0IE
TXIF
TXIE
TXIP
CREN
RBIE
SSPIF
SSPIE
SSPIP
ADDEN
TMR0IF
CCP1IF
CCP1IE
CCP1IP
FERR
INT0IF
TMR2IF
TMR2IE
TMR2IP
OERR
RBIF
TMR1IF
TMR1IE
TMR1IP
RX9D
49
52
52
52
51
51
51
51
51
51
ADIF
ADIE
ADIP
RX9
TX9
RCIDL
TXEN
—
SYNC
SCKP
SENDB
BRG16
BRGH
—
TRMT
WUE
TX9D
ABDEN