Datasheet

Table Of Contents
Section 9 I/O Ports
Rev. 2.00 Jul. 04, 2007 Page 210 of 692
REJ09B0309-0200
Bit Bit Name
Initial
Value
R/W Description
0 SC31S 0 R/W SCI3_1 Pin Assignment Select
0: TXD31 is assigned to P42
RXD31 is assigned to P41
SCK31 is assigned to P40
1: TXD31 is assigned to PF3
RXD31 is assigned to PF2
SCK31 is assigned to PF1
9.16 Usage Notes
9.16.1 How to Handle Unused Pin
If an I/O pin not used by the user system is floating, pull it up or down.
If an unused pin is an input pin, it is recommended to handle it in one of the following ways:
Pull it up to Vcc with an on-chip pull-up MOS.
Pull it up to Vcc with an external resistor of approximately 100 k.
Pull it down to Vss with an external resistor of approximately 100 k.
For a pin also used by the A/D converter, pull it up to AVcc. With an external resistor of
approximately 100 k.
If an unused pin is an output pin, it is recommended to handle it in one of the following ways:
Set the output of the unused pin to high and pull it up to Vcc with an external resistor of
approximately 100 k.
Set the output of the unused pin to low and pull it down to GND with an external resistor of
approximately 100 k.
9.16.2 Input Characteristics Difference due to Pin Function
When the functions of pins IRQ0, IRQ1, IRQ3, IRQ4, IRQACE, WKP0 to WKP7, AEVL,
AEVH, TMIC, TMIF, TMIG, SCK31 to SCK33, SDA, and SCL are selected, the corresponding
pins have the schmitt-trigger input characteristics, which are different from the ones when they are
used as the port input pins.
For example, the input high voltage and the input low voltage of the PB0/AN0/IRQ0 pin differ
when the pin is used as PB0 input or IRQ0 input. For details, refer to tables 26.2 and 26.12.