Hardware manual

Microcomputer Technical Q&A
117
Q&A No.: QAH8S-238
Category: SCI
Subject: Serial Internal I/O Pin States
Question
After the TxD, RxD, and SCK pins—which are multiplexed as I/O ports—were used as SCI pins,
SCI operation was disabled with the serial control register (SCR) and serial mode register (SMR),
and these pins were set as I/O ports.
In this case, what is the data direction register (DDR) value for each of these pins?
Answer
SCI operation does not affect the contents of I/O port data direction registers. Therefore, when the
pins are used as described above, DDR will retain the values it held before the pins were set as
SCI pins. The data register (DR) values are similarly retained.
Applicable Products
Applicability Series Applicability Series Applicability Series
Yes Entire H8S Series H8S/2655 H8S/2350
H8S/2355 H8S/2357 H8S/2345
H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —