R8CSLASH20 datasheet(293/501 Pages) RENESAS

293 / 501 page

R8C/20 Group, R8C/21 Group

15. Serial Interface

Rev.2.00 Aug 27, 2008

Page 277 of 458

REJ09B0250-0200

i = 0 or 1

NOTES:

1. The bits used for transmit/receive data are as follows: Bits 0 to 6 when transfer data is 7-bit long; bits

0 to 7 when transfer data is 8-bit long; bits 0 to 8 when transfer data is 9-bit long.

2. The following bits are undefined: Bits 7 and 8 when transfer data is 7 bits long; bit 8 when transfer

data is 8 bits long.

3. External clock can be selected in UART0 only.

Table 15.6 lists the I/O Pin Functions in UART Mode. After the UARTi (i = 0 or 1) operating mode is selected, the

TXDi pin outputs “H” level (if the NCH bit is set to 1 (N-channel open-drain outputs), this pin is in a high-

impedance state) until transfer starts.

Table 15.5

Registers Used and Settings for UART Mode

Bit

Function

UiTB

0 to 8

Set transmit data(1)

UiRB

0 to 8

Receive data can be read(1, 2)

OER,FER,PER,SUM

Error flag

UiBRG

0 to 7

Set a bit rate

UiMR

SMD2 to SMD0

Set to 100b when transfer data is 7-bit long

Set to 101b when transfer data is 8-bit long

Set to 110b when transfer data is 9-bit long

CKDIR

Select the internal clock or external clock(3)

STPS

Select the stop bit

PRY, PRYE

Select whether parity is included and odd or even

UiC0

CLK0, CLK1

Select the count source for the UiBRG register

TXEPT

Transmit register empty flag

NCH

Select TXDi pin output mode

CKPOL

Set to 0

UFORM

LSB first or MSB first can be selected when transfer data is 8-bit

long. Set to 0 when transfer data is 7- or 9-bit long.

UiC1

Set to 1 to enable transmit

Transmit buffer empty flag

Set to 1 to enable receive

Receive complete flag

UiIRS

Select the UARTi transmit interrupt source

UiRRM

Set to 0

Table 15.6

I/O Pin Functions in UART Mode

Pin name

Function

Selection Method

TXD0(P1_4)

Output serial data

(Cannot be used as a port when performing receive only)

RXD0(P1_5)

Input serial data

The PD1_5 bit in the PD1 register = 0

(P1_5 can be used as an input port when performing transmit only)

CLK0(P1_6)

Programmable I/O port The CKDIR bit in the U0MR register = 0

Input transfer clock

The CKDIR bit in the U0MR register = 1

The PD1_6 bit in the PD1 register = 0

TXD1(P6_6)

Output serial data

U1PINSEL bit in PMR register = 1

(Cannot be used as a port when performing receive only)

RXD1(P6_7)

Input serial data

U1PINSEL bit in PMR register = 1

The PD6_7bit in the PD6 register = 0

(P6_7 can be used as an input port when performing transmit

only)

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