
112
μ
PD75236
(11) Serial interface (channel 1) operations
(a)
Operation stop mode
The operation stop mode is used when serial transfer is not carried out. Power consumption is
decreased in this mode.
In this mode, shift register 1 does not carry out shift operation and thus can be used as a normal
8-bit register.
RESET input sets the operation stop mode. The P82/SO1 pin and P83/SI1 pin are fixed to the input
port. P81/SCK1 can be used as an input port by setting serial operating mode register 1.
(b)
3-wire serial I/O mode operations
The 3-wire serial I/O mode allows connection with the methods employed with another 75X series
and 78K series, etc.
Communication is carried out using three lines of serial clock (SCK1), serial output (SO1) and
serial input (SI1).
The 3-wire serial I/O mode is used for data transmission and reception in 8-bit units. Bit-wise data
transmission/reception is carried out in synchronization with the serial clock.
Shift operation of shift register 1 is carried out at the falling edge of serial clock (SCK1). Transmit
data is held at the SO1 latch and output from the SO1 pin.
Receive data input to the SI1 pin is latched to the shift register 1 at the rising edge of SCK1.
Shift register 1 operation automatically stops upon termination of 8-bit transfer and the serial
transfer end flag (EOT) is set.
Fig. 4-61 3-Wire Serial I/O Mode Timing
SCK1
SI1
SO1
EOT
DO7
DO6
DO5
DO4
DO3
DO2
DO1
DO0
DI7
DI6
DI5
DI4
DI3
DI2
DI1
DI0
1
2
3
4
5
6
7
8
Transfer start at the falling edge of SCK1
Execution of data write instruction to SIO1 (Transfer Start Command)
End of Transfer