NEC switch - Manual (Page 154)

User’s Manual U12978EJ3V0UD
154
CHAPTER 9 SERIAL INTERFACE 10
9.1 Functions of Serial Interface 10
Serial interface 10 has the following two modes.
• Operation stop mode
• 3-wire serial I/O mode
(1) Operation stop mode
This mode is used when serial transfer is not carried out. It enables a reduction in power consumption.
(2) 3-wire serial I/O mode (MSB/LSB start bit switchable)
In this mode, 8-bit data transfer is carried out with three lines: one for the serial clock (SCK10) and two for serial
data (SI10 and SO10).
The 3-wire serial I/O mode supports simultaneous transmit and receive operations, reducing data transfer
processing time.
It is possible to switch the start bit of 8-bit data to be transmitted between the MSB and the LSB, thus allowing
connection to devices with either start bit.
The 3-wire serial I/O mode is effective for connecting display controllers and peripheral I/Os such as the 75XL
Series, 78K Series, and 17K Series that have an internal conventional clocked serial interface.