7480 Datasheet, PDF(32/98 Page) Bi technologies – 7/8 Diameter 5-Turn Wirewound Precision Potentiometer

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7480 Datasheet, PDF (32/98 Pages) Bi technologies – 7/8 Diameter 5-Turn Wirewound Precision Potentiometer

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MITSUBISHI MICROCOMPUTERS

7480/7481 GROUP

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

Serial I/O

Serial I/O can be used as either clock synchronous or asynchro-

nous (UART) serial I/O. A dedicated timer (baud rate generator) is

also provided for baud rate generation when serial I/O is in opera-

tion.

(1) Clock Synchronous Serial I/O Mode

The clock synchronous serial I/O mode can be selected by setting

the serial I/O mode selection bit of the serial I/O control register

(address 00E216) to â1â.

In the clock synchronous serial I/O, the transmitter-side microcom-

puter and the receiver-side microcomputer must use the same

clock for serial I/O operation. If an internal clock is used as oper-

ating clock, a transfer is started by a write signal to the transmit/

receive buffer register.

Data bus

RXD

SCLK

XIN

SRDY

TXD

P16

P14

Receive

enable bit

(RE)

Serial I/O enable bit

(SIOE)

1/4

SRDY output enable

bit (SRDY)

F/F

Transmit enable

bit (TE)

P17

P15

Address 00E016

Receive buffer register

Receive shift register

Shift clock

Serial I/O control register Address 00E216

Receive buffer full flag (RBF)

Receive interrupt request (RI)

Clock control circuit

Serial I/O synchronous

BRG count source Frequency division

clock selection

selection bit (CSS) ratio 1/(n+1)

bit (SCS)

Baud rate generator

1/4

Address 00E416

Falling edge

detection

Clock control circuit

Transmit shift register

Transmit interrupt source

selection bit (TIC)

Transmit buffer register

Address 00E016

Transmit shift register shift completion flag (TSC)

Transmit interrupt request (TI)

Transmit buffer empty flag (TBE)

Serial I/O status register Address 00E116

Data bus

Fig. 28 Block diagram of clock synchronous serial I/O

Transmit/receive shift clock,

1/8 â 1/8192 of internal clock, or

external clock

Serial output TxD

Serial input RxD

Receive enable signal SRDY

Write signal to receive/

transmit buffer register

(address 00E016)

TBE = 0 TBE = 1

TSC = 0

RBF = 1

TSC = 1

Overrun error (OE) detection

Notes 1 : The transmit interrupt (TI) can be selected to be generated either when the transmit buffer is empty (TBE = 1) or after the

transmit shift operation is completed (TSC = 1) by using the transmit interrupt source selection bit (TIC) of the serial I/O control

2 : If data is written to the transmit buffer register when TSC = 0, the transmit clock is generated continuously, and serial data is

output continuously from the TxD pin.

3 : The receive interrupt (RI) is set when the receive buffer full flag (RBF) becomes â1â.

Fig. 29 Operation of clock synchronous serial I/O function

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