CHAPTER 14 SERIAL INTERFACE CHANNEL 0
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14.1 Serial Interface Channel 0 Functions
Serial interface channel 0 employs the following four modes.
Table 14-2. Difference of Serial Interface Channel 0 Mode
Operating Mode
Used Pin
Features
Usage
Operation stop
mode
–
Used when serial transfer is not carried.
Power consumption can be reduced.
–
3-wire serial I/O
mode
SCK0 (serial clock),
SO0 (serial output),
SI0 (serial input)
Input and output lines are independent and
they can transfer/receive at the same time,
so the data transfer processing time is fast.
Since the start bit of 8-bit data to undergo
serial transfer is switchable between MSB
and LSB.
These modes are valid for
connection of peripheral
I/O units and display
controllers which incorporate
a conventional synchronous
clocked serial interface as is
the case with the 75X/XL,
78K and 17K series.
SBI mode
SCK0 (serial clock),
SB0 or SB1 (serial
data bus)
Enables configuration of serial bus with two
signal lines, thus, even when connected to
some microcontrollers, the number of ports
can be cut and the wiring and drawing
around on a board reduced.
High-speed serial interface complying with
the NEC standard bus format.
Address, command and data information onto
the serial bus
The wake-up function for handshake and the
output function of acknowledge signal and
busy signal can also be used.
2-wire serial I/O
mode
SCK0 (serial clock),
SB0 or SB1 (serial
data bus)
Enables to cope with any data transfer format
by program, thus, the handshake lines
previously necessary for connection of two or
more devices can be removed.
Caution
Do not change the operating mode (3-wire serial I/O, 2-wire serial I/O, or SBI) while the
operation of serial interface channel 0 is enabled. To change the operating mode, stop the
serial operation once.