Microchip Technology MCU PIC PIC18F87K22-I/PTRSL TQFP-80 MCP PIC18F87K22-I/PTRSL Data Sheet
Product codes
PIC18F87K22-I/PTRSL
2009-2011 Microchip Technology Inc.
DS39960D-page 347
PIC18F87K22 FAMILY
22.3.2
EUSART SYNCHRONOUS
MASTER RECEPTION
MASTER RECEPTION
Once Synchronous mode is selected, reception is
enabled by setting either the Single Receive Enable bit,
SREN (RCSTAx<5>), or the Continuous Receive
Enable bit, CREN (RCSTAx<4>). Data is sampled on
the RXx 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.
enabled by setting either the Single Receive Enable bit,
SREN (RCSTAx<5>), or the Continuous Receive
Enable bit, CREN (RCSTAx<4>). Data is sampled on
the RXx 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 SPBRGHx:SPBRGx registers for the
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
2.
Enable the synchronous master serial port by
setting bits, SYNC, SPEN and CSRC.
setting bits, SYNC, SPEN and CSRC.
3.
Ensure bits, CREN and SREN, are clear.
4.
If interrupts are desired, set enable bit, RCxIE.
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.
For continuous reception, set bit, CREN.
7.
Interrupt flag bit, RCxIF, will be set when recep-
tion is complete and an interrupt will be generated
if the enable bit, RCxIE, was set.
tion is complete and an interrupt will be generated
if the enable bit, RCxIE, was set.
8.
Read the RCSTAx register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
enabled) and determine if any error occurred
during reception.
9.
Read the 8-bit received data by reading the
RCREGx register.
RCREGx 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.
FIGURE 22-13:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
CREN bit
Write to
bit, SREN
SREN bit
RC1IF bit
(Interrupt)
Read
RCREG1
Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q2
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
‘0’
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
‘0’
Q1 Q2 Q3 Q4
Note:
Timing diagram demonstrates Sync Master mode with bit, SREN = 1, and bit, BRGH = 0. This example is equally applicable to EUSART2
(RG1/TX2/CK2/AN19/C3OUT and RG2/RX2/DT2/AN18/C3INA).
(RG1/TX2/CK2/AN19/C3OUT and RG2/RX2/DT2/AN18/C3INA).
Pin
RC7/RX1/DT1
RC6/TX1/CK1
Pin (TXCKP = 0)
RC6/TX1/CK1
Pin (TXCKP = 1)