Datasheet

M16C/6S Group SI/O3 and SI/O4
R01DS0201EJ0502 Rev.5.02 page 136 of 203
Dec 25, 2012
(c) Functions for Setting an SOUTi Initial Value
If the SiC register’s SMi6 bit = 0 (external clock), the SOUTi pin output can be fixed high or low when not
transferring. Figure 1.17.5 shows the timing chart for setting an SOUTi initial value and how to set it.
Figure 1.17.5. SOUTi’s Initial Value Setting
Setting of the initial value of SOUTi
output and starting of transmission/
reception
Set the SMi3 bit to “0”
(S
OUTi pin functions as an I/O port)
Write to the SiTRR register
Serial transmit/reception starts
Set the SMi7 bit to “1”
(S
OUTi initial value = “H”)
Set the SMi3 bit to “1”
(S
OUTi pin functions as SOUTi output)
“H” level is output
from the S
OUTi pin
Signal written to
SiTRR register
S
OUTi (internal)
SMi7 bit
S
OUTi pin output
SMi3 bit
Setting the S
OUTi
initial value to “H”
Port selection switching
(I/O port S
OUTi)
D0
(i = 3, 4)
Initial value = “H” (Note 3)
Port output
D0
(Example) When “H” selected for SOUTi initial value (Note 1)
Note 1: This diagram applies to the case where the SiC register bits are set as follows:
SMi2=0 (SOUTi output), SMi5=0 (LSB first) and SMi6=0 (external clock)
Note 2: SOUTi can only be initialized when input on the CLKi pin is in the high state if the SiC
register’s SMi4 bit = 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).
Note 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.
(Note 2)