Datasheet

PIC18F6390/6490/8390/8490
DS39629C-page 230 © 2007 Microchip Technology Inc.
17.4.2 AUSART 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
RCREG2 register; if the RC2IE enable bit is set, the
interrupt generated will wake the chip from 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, RC2IE.
3. If 9-bit reception is desired, set bit, RX9.
4. To enable reception, set enable bit, CREN.
5. Flag bit, RC2IF, will be set when reception is
complete. An interrupt will be generated if
enable bit, RC2IE, was set.
6. Read the RCSTA2 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
RCREG2 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 17-9: 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 59
PIR3
— LCDIF RC2IF TX2IF — — — —61
PIE3 — LCDIE RC2IE TX2IE — — — —61
IPR3 — LCDIP RC2IP TX2IP — — — —61
RCSTA2 SPEN RX9 SREN CREN
ADDEN FERR OERR RX9D 63
RCREG2 AUSART2 Receive Register 63
TXSTA2 CSRC TX9 TXEN SYNC — BRGH TRMT TX9D 63
SPBRG2 AUSART2 Baud Rate Generator Register 63
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.