H838532H datasheet(223/508 Pages) RENESAS

223 / 508 page

Section 8 I/O Ports

Rev. 1.00 May 30, 2008 Page 203 of 484

REJ09B0436-0100

8.11.3

Note on Modification of Serial Port Control Register

When a serial port control register is modified, the data being input or output up to that point is

inverted immediately after the modification, and an invalid data change is input or output. When

modifying a serial port control register, do so in a state in which data changes are invalidated.

8.12

Application Note

8.12.1

The Management of the Un-Use Terminal

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, handle it in one of the following ways:

 Pull it up to V

CC with an on-chip pull-up MOS.

 Pull it up to V

CC with an external resistor of approximately 100 kΩ.

 Pull it down to V

SS with an external resistor of approximately 100 kΩ.

 For a pin also used by the A/D converter, pull it up to AV

CC.

• If an unused pin is an output pin, handle it in one of the following ways:

 Set the output of the unused pin to high and pull it up to V

CC with an external resistor of

approximately 100 k

Ω.

 Set the output of the unused pin to low and pull it down to V

SS with an external resistor of

approximately 100 k

Ω.

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