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M16C/62P Group (M16C/62P, M16C/62PT)
17.2.3 Functions for Setting an S
If the SMi6 bit in the SiC register = 0 (external clock), the SOUTi pin output can be fixed high or low when
not transferring. Figure 17.38 shows the timing chart for setting an SOUTi initial value and how to set it.
(Example) When "H" Selected for SOUTi Initial Value
Signal written to
SiTRR register
SMi7 bit
SMi3 bit
SOUTi (internal)
Port output
SOUTi pin output
(i = 3, 4)
Setting the SOUTi
initial value to "H"
NOTES:
1. This diagram applies to the case where the bits in the SiC register are set as follows:
SMi2 = 0 (SOUTi output), SMi5 = 0 (LSB first) and SMi6 = 0 (external clock)
2. SOUTi can only be initialized when input on the CLKi pin is in the high state if the
SMi4 bit in the SiC register = 0 (transmit data output at the falling edge of the transfer clock)
or in the low state if the SMi4 bit = 1 (transmit data output at the rising edge of the
transfer clock).
3. If the SMi6 bit = 1 (internal clock) or if the SMi2 bit = 1 (SOUT output disabled),
this output goes to the high-impedance state.
Figure 17.38 SOUTi's Initial Value Setting
R
e
. v
2
3 .
0
S
e
p
0
, 1
2
0
0
4
R
E
J
0
9
B
0
1
8
5
0 -
2
3
0
Z
(1)
Initial value = H
Port selection switching
(2)
(I/O port
SOUTi)
page 206
f o
3
6
4
i Initial Value
OUT
D0
D0
(3)
17. Serial I/O
Setting of the initial value of SOUTi
output and starting of transmission/
reception
Set the SMi3 bit to "0"
(SOUTi pin functions as an I/O port)
Set the SMi7 bit to "1"
(SOUTi initial value = H)
Set the SMi3 bit to "1"
(SOUTi pin functions as
SOUTi output)
"H" level is output
from the SOUTi pin
Write to the SiTRR register
Serial transmit/reception starts
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