M38C88EA-XXXFP Просмотр технического описания (PDF) - MITSUBISHI ELECTRIC

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M38C88EA-XXXFP

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI ELECTRIC  

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MITSUBISHI MICROCOMPUTERS

38C8 Group

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

SERIAL I/O

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

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

provided for baud rate generation.

(1) Clock Synchronous Serial I/O Mode

Clock synchronous serial I/O can be selected by setting the mode

selection bit of the serial I/O control register to “1”.

For clock synchronous serial I/O, the transmitter and the receiver

must use the same clock. If an internal clock is used, transfer is started

by a write signal to the transmit/receive buffer registers.

P44/RXD

Data bus

Address 001816

Receive buffer register

Serial I/O control register

Address 001A16

Receive buffer full flag (RBF)

Receive shift register

Shift clock

Receive interrupt request (RI)

Clock control circuit

P46/SCLK

BRG count source selection bit

f(XIN)

(f(XCIN) in low-speed mode)

1/4

Serial I/O

clock selection bit

Frequency division ratio 1/(n+1)

Baud rate generator

1/4

Address 001C16

P47/SRDY

P45/TXD

F/F

Falling-edge detector

Clock control circuit

Shift clock

Transmit shift register shift completion flag (TSC)

Transmit interrupt source selection bit

Transmit shift register

Transmit interrupt request (TI)

Transmit buffer register

Address 001816

Data bus

Transmit buffer empty flag (TBE)

Serial I/O status register

Address 001916

Fig. 20 Block diagram of clock synchronous serial I/O

Transmit/receive shift clock

(1/2 to 1/2048 of internal clock,

or an external clock)

Serial output TXD

Serial input RXD

D0

D1

D2

D3

D4

D5

D6

D7

D0

D1

D2

D3

D4

D5

D6

D7

Receive enable signal SRDY

Write signal to receive/transmit

buffer register (address 001816)

TBE = 0 TBE = 1

TSC = 0

RBF = 1

TSC = 1

Overrun error (OE)

detection

Notes 1: The transmit interrupt (TI) can be selected to occur either when the transmit buffer register has emptied (TBE=1) or after

the transmit shift operation has ended (TSC=1), by setting the transmit interrupt source selection bit (TIC) of the serial

I/O control register.

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 “1” .

Fig. 21 Operation of clock synchronous serial I/O function

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