7480 datasheet(146/337 Pages) RENESAS

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7480 Group and 7481 Group User's Manual

1-129

1.14 Serial I/O

HARDWARE

Name

Start Bit

(ST)

Data Bits

(DATA)

Parity Bit

(PA)

Stop Bit(s)

(SP)

Function

Indicates the start of data transmission. The LOW signal of one-bit wide is added to the

head of the transmit data.

The transmit data written into UART transmit buffer register.

Data ‘0’ represents LOW, and ‘1’ the HIGH signal.

Added to the end of the data bits to enhance the reliability of communications. The number

of ‘1’ in transmit/receive data including parity bit keeps even or odd according to the setting

value of parity selection bit.

Added to the end of the data bits (or after the parity bit if parity is valid) and indicates the

transmission is completed. The HIGH signal of one or two bits wide is output as stop bit.

Table 1.14.4 Function of UART Transfer Data Bits

(1)

Block Diagram of UART

Figure 1.14.16 shows the block diagram of UART.

Figure 1.14.16 Block Diagram of UART

P14

P16 P15

1/4

Clock control circuit

(TE)

(RE)

RxD

SCLK

XIN

TxD

SP detection

ST/SP/PA generation

Overrun error

flag(OE)

1/16

1/4

Framing error flag (FE)

Parity error flag (PE)

Character length

selection bit (CHAS)

1/16

Serial I/O synchronous clock selection bit (SCS)

Transmit interrupt source

selection bit (TIC)

Receive buffer full flag (RBF)

Receive interrupt request (RI)

Division ratio 1/(n + 1)

Address 00E016

Receive buffer register

Receive shift register

Transmit buffer register

Transmit shift register

Serial I/O status register

Address 00E116

Serial I/O control register

Baud rate generator

Transmit shift completion flag (TSC)

Transmit interrupt request (TI)

Transmit buffer empty flag (TBE)

Serial I/O synchronous clock

selection bit (SCS)

BRG count source

selection bit (CSS)

Transmit enable bit

Receive enable bit

Address 00E416

Serial I/O enable bit(SIOE)

Data bus

Address 00E016

Address 00E216

ST detection

7 bits

8 bits

UART control register

Address 00E316

Character length

selection bit (CHAS)

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