Datasheet
PIC16F87/88
DS30487D-page 112 2002-2013 Microchip Technology Inc.
11.4.2 AUSART 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 11-13: 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 INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
0Ch PIR1
— ADIF
(1)
RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF -000 0000 -000 0000
18h RCSTA SPEN RX9
SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x
1Ah RCREG AUSART Receive Data Register 0000 0000 0000 0000
8Ch PIE1
— ADIE
(1)
RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE -000 0000 -000 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: This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.