Renesas H8S/2633 Series Hardware Manual page 516

Pin Selection Method and Pin Functions
P31/RxD0 Switches as follows according to combinations of SCR RE bit of SCI0 and the
P31DDR bit.
RE
P31DDR
Pin function
Note: * When P31ODR = 1, it becomes NMOS open drain output.
P30/TxD0 Switches as follows according to combinations of SCR TE bit of SCI0 and the
P30DDR bit.
TE
P30DDR
Pin function
Note: * When P30ODR = 1, it becomes NMOS open drain output.
462
0
0
P31 input pin P31 output pin*
0
0
P30 input pin P30 output pin*
1
RxD0 input pin
1
TxD0 output pin*
1
—
1
—