R8CSLASH15 datasheet(202/277 Pages) RENESAS

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R8C/14 Group, R8C/15 Group

17. Programmable I/O Ports

Rev.2.10

Jan 19, 2006

Page 190 of 253

REJ09B0164-0210

17.5

Unassigned Pin Handling

Table 17.18 lists the Unassigned Pin Handling. Figure 17.9 show the Unassigned Pin Handling.

NOTES:

1. When setting these ports to output mode and leaving them open, they remain input mode until they

are switched to output mode by a program. The voltage level of these pins may be indeterminate

and the power current may increase while the ports remain input mode.

The content of the direction registers may change due to noise or out of control caused by noise. In

order to enhance program reliability, set the direction registers periodically by a program.

2. Connect these unassigned pins to the microcomputer using the shortest wire length (within 2 cm)

as possible.

3. When power-on reset function is used.

Figure 17.9

Unassigned Pin Handling

Table 17.18

Unassigned Pin Handling

Pin Name

Connection

Ports P1, P3_3 to P3_5,

P3_7, P4_5

• After setting to input mode, connect every pin to VSS via a resistor (pull-

down) or connect every pin to VCC via a resistor (pull-up).(2)

• After setting to output mode, leave these pins open.(1, 2)

Ports P4_6, P4_7

Connect to VCC via a resistor (pull-up)(2)

AVCC, VREF

Connect to VCC

RESET (3)

Connect to VCC via a resistor (pull-up)(2)

NOTES:

1. When power-on reset function is used.

Microcomputer

Port P1, P3_3 to P3_5,

P3_7, P4_5

(Input mode)

(Output mode)

Port P4_6, P4_7

RESET(1)

AVCC/VREF

Open

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