M16C6S_09 Datasheet, PDF (136/208 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6S Group
SI/O3 and SI/O4
(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.
(Example) When “H” selected for SOUTi initial value (Note 1)
Signal written to
SiTRR register
SMi7 bit
SMi3 bit
D0
SOUTi (internal)
Port output
D0
SOUTi pin output
Initial value = “H” (Note 3)
(i = 3, 4)
Setting the SOUTi
initial value to “H”
(Note 2)
Port selection switching
(I/O port SOUTi)
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.
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”
(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
Rev.5.01 Dec 10, 2009 page 136 of 201
REJ03B0014-0501