15. Serial Interface - Renesas R8C/18 Series Hardware Manual

R8C/18 Group, R8C/19 Group

15. Serial Interface

The serial interface consists of two channels (UART0 and UART1). Each UARTi (i = 0 or 1) has an exclusive
timer to generate the transfer clock and operates independently.
Figure 15.1 shows a UARTi (i = 0 or 1) Block Diagram. Figure 15.2 shows a UARTi Transmit/Receive Unit.
UART0 has two modes: clock synchronous serial I/O mode and clock asynchronous serial I/O mode (UART
mode).
UART1 has only clock asynchronous serial I/O mode (UART mode).
Figures 15.3 to 15.6 show the Registers Associated with UARTi.
(UART0)
RXD0
CLK1 to CLK0 = 00b
f1
= 01b
f8
= 10b
f32
CLK
polarity
CLK0
reversing
circuit
(UART1)
RXD1
CLK1 to CLK0
= 00b
f1
= 01b
f8
= 10b
f32
Figure 15.1 UARTi (i = 0 or 1) Block Diagram
Rev.1.30 Apr 14, 2006
REJ09B0222-0130
UART reception
1/16
CKDIR = 0
Internal
synchronous type
U0BRG register
UART transmission
1/(n0+1) 1/16
External synchronous type
CKDIR = 1
1/2
Clock synchronous type
(when internal clock is selected)
Clock synchronous type
(when external clock is selected)
Clock synchronous type
(when internal clock is selected)
UART reception
1/16
U1BRG
Internal register
UART transmission
1/(n1+1) 1/16
Page 146 of 233
Receive
clock
Reception control
Clock
circuit
Transmit
clock
Transmission
Clock
control circuit
CKDIR = 0
CKDIR = 1
Receive clock
Reception
control circuit
Transmit clock
Transmission
control circuit
15. Serial Interface
TXD0
Transmit/
receive
unit
TXD1
Transmit/
receive
unit