Technical information

2-32

3800 GROUP USER’S MANUAL

APPLICATION

2.3 Serial I/O

Serial I/O status register (Address : 1916)

SIOSTS

Baud rate generator (Address : 1C16)

BRG

Set “division ratio – 1”

Transmit buffer empty flag

• Check to be transferred data from the Transmit buffer register to

Transmit shift register.

• Writable the next transmission data to the Transmit buffer register

at being set to “1.”

Transmitting side

Transmit shift register shift completion flag

Check a completion of transmitting 1-byte data with this flag

“1” : Transmit shift completed

Serial I/O control register (Address : 1A16)

SIOCON

BRG counter source selection bit : f(XIN)

Serial I/O synchronous clock selection bit : BRG/4

Transmit enable bit : Transmit enabled

Receive enable bit : Receive disabled

Serial I/O mode selection bit : Clock synchronous serial I/O

Serial I/O enable bit : Serial I/O enabled

Interrupt edge selection register (Address : 3A16)

INTEDGE

INT0 active edge selection bit : Select INT0 falling edge

b7 b0

1101 00

b7 b0

Fig. 2.3.15 Setting of related registers at a transmitting side [Communication using a clock

synchronous serial I/O]