147
Mitsubishi microcomputers
M16C / 62T Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
S I/O3, 4
Functions for setting an SOUTi initial value
When using an external clock for the transfer clock, the SOUTi pin output level during a non-transfer
time can be set to the high or the low state. Figure 1.19.31 shows the timing chart for setting at SOUTi
initial value and how to set it.
Figure 1.19.31. Timing chart for setting SOUTi’s initial value and how to set it
S I/Oi operation timing
Figure 1.19.32 shows the S I/Oi operation timing
Figure 1.19.32. S I/Oi operation timing chart
S I/Oi port select bit SMi3 = 0
SOUTi initial value select bit
SMi7 = 1
(SOUTi: Internal
“H” level)
S I/Oi port select bit
SMi3 = 0
1
(Port select: Normal port
SOUTi)
SOUTi terminal = “H” output
Signal written to the S I/Oi register
=“L”
“H”
“L”
(Falling edge)
SOUTi terminal = Outputting
stored data in the S I/Oi transmission/
reception register
Signal written to the S I/Oi
transmission/reception
register
SOUTi (internal)
SOUTi's initial value
set bit (SMi7)
SOUTi terminal output
S I/Oi port select bit
(SMi3)
Setting the SOUTi
initial value to H
Port selection
(normal port
SOUTi)
D0
(i = 3, 4)
Initial value = “H” (Note)
Port output
D0
(Example) With “H” selected for SOUTi:
Note: The set value is output only when the external clock has been selected.
When initializing SOUTi, make sure the CLKi pin input is held “L” level.
If the internal clock has been selected or if SOUT output disable has been
set, this output goes to the high-impedance state.
D7
D0
D1
D2
D3
D4
D5
D6
Transfer clock
(Note 1)
S I/Oi output SOUTi
S I/Oi input SINi
Signal written to
the S I/Oi register
(Note 2)
Note 1: With the internal clock selected for the transfer clock, the frequency dividing ratio can be selected using
bits 0 and 1 of the S I/Oi control register. (No frequency division, 8-division frequency, 32-division frequency.)
Note 2: With the internal clock selected for the transfer clock, the SOUTi terminal becomes to the high-impedance
state after the transfer finishes.
Note 3: In M30623(80-pin package), the input pin SIN3 of S I/O3 is not connected to external pin.
Note 4: Shown above is the case where the SOUTi (i = 3, 4) port select bit = “1”.
(i= 3, 4)
(Note 3)
Transfer clock
(Note 1)
Hiz
1.5 cycle (max)
(i= 3, 4)
“H”
“L”
“H”
“L”
“H”
“L”
“H”
“L”
“H”
“L”
“1”
“0”
Setting the S I/Oi
interrupt request bit