Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
S I/O3, 4
146
Functions for setting an S
OUT
i initial value
When using an external clock for the transfer clock, the S
OUTi
pin output level during a non-transfer
time can be set to the high or the low state. Figure 1.16.33 shows the timing chart for setting an S
OUTi
initial value and how to set it.
Figure 1.16.33. Timing chart for setting SOUTi
’
s initial value and how to set it
S I/Oi operation timing
Figure 1.16.34 shows the S I/Oi operation timing
D
7
D
0
D
1
D
2
D
3
D
4
D
5
D
6
(i= 3, 4)
(i= 3, 4)
Hiz
Hiz
(i= 3, 4)
1.5 cycle (max)
SI/Oi internal clock
Transfer clock
(Note 1)
Signal written to the
S I/Oi register
S I/Oi output S
OUT
i
S I/Oi input S
IN
i
SI/Oi interrupt request
bit
Note2
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. (i=3,4) (No frequency division, 8-division frequency, 32-division frequency.)
Note 2:With the internal clock selected for the transfer clock, the S
OUT
i (i = 3, 4) pin becomes to the high-impedance state after the transfer finishes.
Note 3:Shown above is the case where the S
OUT
i (i = 3, 4) port select bit =“1”.
"H"
"L"
"H"
"L"
"H"
"L"
"H"
"L"
"H"
"L"
"1"
"0"
Figure 1.16.34. S I/Oi operation timing chart
S I/Oi port select bit SMi3 = 0
SOUTi initial value select bit
SMi7 = 1
(S
OUT
i: Internal “H” level)
S I/Oi port select bit
SMi3 = 0 1
(Port select: Normal port S
OUT
i)
S
OUT
i terminal = “H” output
Signal written to the S I/Oi register
=“L” “H” “L”
(Falling edge)
S
OUT
i terminal = Outputting
stored data in the S I/Oi transmission/
reception register
Signal written to the S I/Oi
transmission/reception
register
S
OUT
i (internal)
S
OUT
i's initial value
set bit (SMi7)
S
OUT
i terminal output
S I/Oi port select bit
(SMi3)
Setting the S
OUT
i
initial value to H
Port selection
(normal port S
OUT
i)
D0
(i = 3, 4)
Initial value = “H” (Note)
Port output
D0
(Example) With “H” selected for S
OUT
i:
Note: The set value is output only when the external clock has been selected. When
initializing S
OUT
i, make sure the CLKi pin input is held “H” level.
If the internal clock has been selected or if S
OUT
output disable has been set,
this output goes to the high-impedance state.