PIC18FXX39 Datasheet, PDF (178/322 Pages) Microchip Technology – Enhanced FLASH Microcontrollers with Single Phase Induction Motor Control Kernel

PIC18FXX39
17.3.2 USART SYNCHRONOUS MASTER
RECEPTION
Once Synchronous mode is selected, reception is
enabled by setting either enable bit SREN
(RCSTA<5>), or enable bit CREN (RCSTA<4>). Data is
sampled on the RC7/RX/DT pin on the falling edge of
the clock. If enable bit SREN is set, only a single word
is received. If enable bit CREN is set, the reception is
continuous until CREN is cleared. If both bits are set,
then CREN takes precedence.
To set up a Synchronous Master Reception:
1. Initialize the SPBRG register for the appropriate
baud rate (Section 17.1).
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
3. Ensure bits CREN and SREN are clear.
4. If interrupts are desired, set enable bit RCIE.
5. If 9-bit reception is desired, set bit RX9.
6. If a single reception is required, set bit SREN.
For continuous reception, set bit CREN.
7. Interrupt flag bit RCIF will be set when reception
is complete and an interrupt will be generated if
the enable bit RCIE was set.
8. Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
9. Read the 8-bit received data by reading the
RCREG register.
10. If any error occurred, clear the error by clearing
bit CREN.
11. 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 MASTER RECEPTION
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
INTCON GIE/ PEIE/ TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 0000 000u
GIEH GIEL
PIR1
PSPIF⁽¹⁾ ADIF RCIF TXIF SSPIF
— _{TMR2IF TMR1IF 0000 0000 0000 0000}
PIE1
IPR1
PSPIE⁽¹⁾ ADIE
PSPIP⁽¹⁾ ADIP
RCIE
RCIP
TXIE SSPIE
TXIP SSPIP
— _{TMR2IE TMR1IE 0000 0000 0000 0000}
— _{TMR2IP TMR1IP 0000 0000 0000 0000}
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 -00x 0000 -00x
RCREG USART Receive Register
0000 0000 0000 0000
TXSTA CSRC TX9 TXEN SYNC — BRGH TRMT TX9D 0000 -010 0000 -010
SPBRG Baud Rate Generator Register
0000 0000 0000 0000
Legend: x = unknown, - = unimplemented, read as '0'. Shaded cells are not used for Synchronous Master Reception.
Note 1: The PSPIF, PSPIE and PSPIP bits are reserved on the PIC18F2X39 devices; always maintain these bits clear.
FIGURE 17-8:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
RC7/RX/DT pin
bit0
bit1
bit2
bit3
bit4
bit5
bit6
bit7
RC6/TX/CK pin
Write to
bit SREN
SREN bit
CREN bit ^'0'
'0'
RCIF bit
(Interrupt)
Read
RXREG
Note: Timing diagram demonstrates Sync Master mode with bit SREN = '1' and bit BRGH = '0'.
DS30485B-page 178
Preliminary
 2002-2013 Microchip Technology Inc.