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Chapter 14
Serial Interface SIO31
User’s Manual U16504EE1V1UD00
(3)
3-wire Communication Operations
In the three-wire serial I/O mode, data is transmitted and received in 8-bit units. Each bit of data is
sent or received synchronized with the serial clock.
The serial I/O shift register (SIO31) is shifted synchronized with the falling edge of the serial clock.
The transmission data is held in the SO31 latch and is transmitted from the SO31 pin. The data is
received via the SI31 pin synchronized with the rising edge of the serial clock is latched to SIO31.
The completion of an 8-bit transfer automatically stops operation of SIO31 and sets a serial trans-
fer completion flag.
Figure 14-9:
Timing of Three-wire Serial I/O Mode
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In the two-wire serial I/O mode, data is transmitted and received in 8-bit units. Each bit of data is sent or
received synchronized with the serial clock.
The serial I/O shift register 31 (SIO31) is shifted synchronized with the falling edge of the serial clock.
The transmission data is held in the SIO31 latch and is transmitted from the SIO31 pin. The data is
received via the SIO31 pin synchronized with the rising edge of the serial clock is latched to SIO31.
The completion of an 8-bit transfer automatically stops operation of SIO31 and sets interrupt request
flag.
2-wire Communication Operations
Figure 14-10:
Timing of Two-wire Serial I/O Mode
SI31
DI7
DI6
DI5
DI4
DI3
DI2
DI1
DI0
Serial transfer
completion flag
SCK31
1
SO31
DO7
DO6
DO5
DO4
DO3
DO2
DO1
DO0
2
3
4
5
6
7
8
Transfer completion
Transfer starts in synchronized with the serial clock’s falling edge
Data input SIO31
DI7
DI6
DI5
DI4
DI3
DI2
DI1
DI0
Serial transfer
completion flag
SCK31
1
Data output SIO31
DO7
DO6
DO5
DO4
DO3
DO2
DO1
DO0
2
3
4
5
6
7
8
Transfer completion
Transfer starts in synchronized with the serial clock’s falling edge