NEC uPD78P078 - Manual (Page 317)

CHAPTER 17 SERIAL INTERFACE CHANNEL 0 (
µ
PD78078 SUBSERIES)
317
Master CPU
SCK0
SB0
SCK0
SB0
Slave CPU1
SCK0
SB0
Slave CPU2
SCK0
SB0
Slave CPUn
V DD0
(4) 2-wire serial I/O mode (MSB-first)
This mode is used for 8-bit data transfer using two lines of serial clock (SCK0) and serial data bus (SB0
or SB1).
This mode enables to cope with any one of the possible data transfer formats by controlling the SCK0 level
and the SB0 or SB1 output level. Thus, the handshake line previously necessary for connection of two or
more devices can be removed, resulting in the increased number of available input/output port pins.
Figure 17-1. Serial Bus Interface (SBI) System Configuration Example