M306H7MG-XXXFP Datasheet, PDF (142/329 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with DATA ACQUISITION CONTROLLER

M306H7MG-XXXFP/MC-XXXFP/FGFP
10. SERIAL I/O
10.8.3 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 10.38 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.
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
Figure 10.38 SOUTi’s Initial Value Setting
Rev.2.10 Oct 25, 2006 Page 142 of 326
REJ03B0152-0210