Datasheet

Table Of Contents
PIC18F87J72 FAMILY
DS39979A-page 258 Preliminary 2010 Microchip Technology Inc.
19.5.2 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
RCREG1 register; if the RC1IE enable bit is set, the
interrupt 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, RC1IE.
3. If 9-bit reception is desired, set bit, RX9.
4. To enable reception, set enable bit, CREN.
5. Flag bit, RC1IF, will be set when reception is
complete. An interrupt will be generated if
enable bit, RC1IE, was set.
6. Read the RCSTA1 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
RCREG1 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 19-10: 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 GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1
ADIF RC1IF TX1IF SSPIF TMR2IF TMR1IF 52
PIE1 ADIE RC1IE TX1IE SSPIE TMR2IE TMR1IE 52
IPR1 ADIP RC1IP TX1IP SSPIP TMR2IP TMR1IP 52
RCSTA1 SPEN RX9 SREN CREN
ADDEN FERR OERR RX9D 51
RCREG1 EUSART Receive Register 51
TXSTA1 CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON1
ABDOVF RCMT RXDTP TXCKP BRG16 WUE ABDEN 53
SPBRGH1 EUSART Baud Rate Generator Register High Byte 53
SPBRG1 EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented, read as ‘0. Shaded cells are not used for synchronous slave reception.