4-4
UP-D70/D70A (UC,CE)
c) Transmission control between each board
Serial communication between each board (SY-270 board
⇔
other board) is performed by time
division mutual toward one system.
Sequence of this timing division is performed as follows. Baud rate is 31250bps.
• When receiving (Child data
⇒
SY-270 board)
• When transmitting (SY-270 board data
⇒
Child)
1) Before data sending, child
board sets nARB to L.
2) SY-270 board ensures
nARB to L, SY-270
board stops rotation of
nSEL and lowers nRTS.
3) Child board sends the data
1byte.
4) SY-270 board rises RTS,
child rises nARB.
5) When nARB is risen, SY-
270 board performs
rotation again.
1) SY-270 board stops
rotation by child which
want to send nSEL.
2) SY-270 board sends 1byte
data.
3) Child board rises RTS.
CTS is risen by beating
clock of IC307 (D,FF) on
SY-270 board.
4) SY-270 board ensures
CTS was risen, and clears
CTS again to perform
rotation again.
