
96
μ
PD75236
(5)
Serial interface (channel 0) 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 0 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 P02/SO0/SB0 pin and P03/SI0/SB1 pins are fixed to
the input port. P01/SCK0 can be used as an input port by setting serial operating mode register 0.
(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.
Communication is carried out using three lines of serial clock (SCK0), serial output (SO0) and
serial input (SI0).
(i)
Communication
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 0 is carried out at the falling edge of serial clock (SCK0). Transmit
data is held at the SO0 latch and output from the SO0 pin. Receive data input to the SI0 pin is latched
to the shift register 0 at the rising edge of SCK0.
Shift register 0 operation automatically stops upon termination of 8-bit transfer and the interrupt
request flag (IRQCSI0) is set.
Fig. 4-49 3-Wire Serial I/O Mode Timing
SCK0
SI0
SO0
IRQCSI0
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 SCK0
Execution of data write instruction to SIO0
(Transfer Start Command)
End of Transfer