PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 191

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

18.2.2
The receiver block diagram is shown in Figure 18-4.
The data is received on the RC7/RX/DT pin and drives
the data recovery block. The data recovery block is
actually a high speed shifter, operating at x16 times the
baud rate, whereas the main receive serial shifter oper-
ates at the bit rate, or at F
typically be used in RS-232 systems.
Steps to follow when setting up an Asynchronous
Reception:
1.
2.
3.
4.
5.
6.
7.
8.
9.
FIGURE 18-4:
 2002 Microchip Technology Inc.
Initialize the SPBRG register for the appropriate
baud rate. If a high speed baud rate is desired,
set bit BRGH (Section 18.1).
Enable the asynchronous serial port by clearing
bit SYNC and setting bit SPEN.
If interrupts are desired, set enable bit RCIE.
If 9-bit reception is desired, set bit RX9.
Enable the reception by setting bit CREN.
Flag bit RCIF will be set when reception is com-
plete and an interrupt will be generated if enable
bit RCIE was set.
Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
Read the 8-bit received data by reading the
RCREG register.
If any error occurred, clear the error by clearing
enable bit CREN.
Note: I/O pins have diode protection to V
USART ASYNCHRONOUS
RECEIVER
RC7/RX/DT
Baud Rate Generator
x64 Baud Rate CLK
USART RECEIVE BLOCK DIAGRAM
SPBRG
and Control
Pin Buffer
SPEN
OSC
. This mode would
DD
and V
Recovery
Data
Interrupt
SS
Preliminary
.
CREN
÷ 64
÷ 16
or
18.2.3
This mode would typically be used in RS-485 systems.
Steps to follow when setting up an Asynchronous
Reception with Address Detect Enable:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. If any error occurred, clear the CREN bit.
11. If the device has been addressed, clear the
RCIF
RCIE
RX9
Initialize the SPBRG register for the appropriate
baud rate. If a high speed baud rate is required,
set the BRGH bit.
Enable the asynchronous serial port by clearing
the SYNC bit and setting the SPEN bit.
If interrupts are required, set the RCEN bit and
select the desired priority level with the RCIP bit.
Set the RX9 bit to enable 9-bit reception.
Set the ADDEN bit to enable address detect.
Enable reception by setting the CREN bit.
The RCIF bit will be set when reception is com-
plete. The interrupt will be Acknowledged if the
RCIE and GIE bits are set.
Read the RCSTA register to determine if any
error occurred during reception, as well as read
bit 9 of data (if applicable).
Read RCREG to determine if the device is being
addressed.
ADDEN bit to allow all received data into the
receive buffer and interrupt the CPU.
STOP
MSb
RX9D
(8)
SETTING UP 9-BIT MODE WITH
ADDRESS DETECT
OERR
7
RSR Register
RCREG Register
• • •
8
Data Bus
PIC18FXX8
1
FERR
0
START
LSb
DS41159B-page 189
FIFO