Function For Setting Souti Initial Value - Renesas M16C/64A Series User Manual

M16C/64A Group
24.3.8

Function for Setting SOUTi Initial Value

When the SMi6 bit in the SiC register is 0 (external clock), the SOUTi pin output can be fixed high or low
when not transmitting/receiving data. High or low can be selected by setting the SMi7 bit in the SiC
register. However, the last bit value of the previous unit of data is retained between adjacent units of data
when using the external clock. Figure 24.7 shows Timing Chart for Setting SOUTi Initial Value and How to
Set It.
(Example) When High Is Selected for the SOUTi Initial Value
Write signal to the
SiTRR register
SMi7 bit
SMi3 bit
SOUTi (internal)
SOUTi pin output
(i = 3, 4)
Setting the SOUTi
initial value to high
This diagram assumes the following:
SMi2 = 0 (SOUTi output), SMi5 = 0 (LSB first), SMi6 = 0 (external clock)
Note:
1. 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 is output at the falling edge of the transmit
receive clock) or in the low state if the SMi4 bit = 1 (transmit data is output at the rising
edge of the transmit/receive clock).
Figure 24.7 Timing Chart for Setting SOUTi Initial Value and How to Set It
R01UH0136EJ0210 Rev.2.10
Jul 31, 2012
Port output
Port selection switching
(I/O port → SOUTi)
(1)
D0
D0
Initial value = high
24. Serial Interface SI/O3 and SI/O4
Initial value setting of SOUTi output
and transmission/reception start
Set the SMi3 bit to 0
(SOUTi pin functions as an I/O port)
Set the SMi7 bit to 1
(SOUTi initial value = high)
Set the SMi3 bit to 1
(SOUTi pin functions as SOUTi output)
High is output from
the SOUTi pin
Write to the SiTRR register
Serial transmission/
reception starts
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