Datasheet

Table Of Contents
PIC16F631/677/685/687/689/690
DS41262E-page 176 © 2008 Microchip Technology Inc.
12.4.2.3 EUSART Synchronous Slave
Reception
The operation of the Synchronous Master and Slave
modes is identical (Section 12.4.1.5 “Synchronous
Master Reception”), with the following exceptions:
Sleep
CREN bit is always set, therefore the receiver is
never Idle
SREN bit, which is a “don't care” in Slave mode
A character may be received while in Sleep mode by
setting the CREN bit prior to entering Sleep. Once the
word is received, the RSR register will transfer the data
to the RCREG register. If the RCIE enable bit is set, the
interrupt generated will wake the device from Sleep
and execute the next instruction. If the GIE bit is also
set, the program will branch to the interrupt vector.
12.4.2.4 Synchronous Slave Reception
Set-up:
1. Set the SYNC and SPEN bits and clear the
CSRC bit.
2. If interrupts are desired, set the RCIE bit of the
PIE1 register and the GIE and PEIE bits of the
INTCON register.
3. If 9-bit reception is desired, set the RX9 bit.
4. Set the CREN bit to enable reception.
5. The RCIF bit will be set when reception is
complete. An interrupt will be generated if the
RCIE bit was set.
6. If 9-bit mode is enabled, retrieve the Most
Significant bit from the RX9D bit of the RCSTA
register.
7. Retrieve the 8 Least Significant bits from the
receive FIFO by reading the RCREG register.
8. If an overrun error occurs, clear the error by
either clearing the CREN bit of the RCSTA
register or by clearing the SPEN bit which resets
the EUSART.
TABLE 12-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
NameBit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
Value on
POR, BOR
Value on
all other
Resets
BAUDCTL
ABDOVF RCIDL —SCKPBRG16 WUE ABDEN 01-0 0-00 01-0 0-00
INTCON GIE PEIE
T0IE INTE RABIE T0IF INTF RABIF 0000 000x 0000 000x
PIE1
ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 0000
PIR1
ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
RCREG EUSART Receive Data Register 0000 0000 0000 0000
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
SPBRG
BRG7 BRG6 BRG5 BRG4 BRG3 BRG2 BRG1 BRG0 0000 0000 0000 0000
SPBRGH
BRG15 BRG14 BRG13 BRG12 BRG11 BRG10 BRG9 BRG8 0000 0000 0000 0000
TRISB TRISB7
TRISB6 TRISB5 TRISB4 1111 ---- 1111 ----
TXREG
EUSART Transmit Data Register 0000 0000 0000 0000
TXSTA CSRC TX9 TXEN SYNC SENDB
BRGH TRMT TX9D 0000 0010 0000 0010
Legend: x = unknown, – = unimplemented read as0’. Shaded cells are not used for Synchronous Slave Reception.