Unassigned Pin Handling - Renesas R8C/18 Series Hardware Manual

R8C/18 Group, R8C/19 Group
6.5

Unassigned Pin Handling

Table 6.18 lists Unassigned Pin Handling. Figure 6.9 shows Unassigned Pin Handling.
Table 6.18 Unassigned Pin Handling
Pin Name
Ports P1, P3_3 to P3_5,
P3_7, P4_5
Ports P4_6, P4_7
Port P4_2/VREF
(3)
RESET
NOTES:
1. If these ports are set to output mode and left open, they remain in input mode until they are switched
to output mode by a program. The voltage level of these pins may be undefined and the power
supply current may increase while the ports remain in input mode.
The content of the direction registers may change due to noise or program runaway caused by
noise. In order to enhance program reliability, the program should periodically repeat the setting of
the direction registers.
2. Connect these unassigned pins to the MCU using the shortest wire length (2 cm or less) possible.
3. When the power-on reset function is in use.
Figure 6.9 Unassigned Pin Handling
Rev.1.30 Apr 14, 2006
REJ09B0222-0130
• After setting to input mode, connect each pin to VSS via a resistor (pull-
down) or connect each pin to VCC via a resistor (pull-up).
• After setting to output mode, leave these pins open.
Connect to VCC via a pull-up resistor
Connect to VCC
Connect to VCC via a pull-up resistor
MCU
Port P1, P3_3 to P3_5, (Input mode)
P3_7, P4_5
(Input mode)
(Output mode)
Port P4_6, P4_7
Port P4_2/VREF
NOTE:
1. When the power-on reset function is in use.
Page 39 of 233
Connection
(2)
(2)
:
:
:
:
Open
(1)
RESET
6. Programmable I/O Ports
(2)
(1, 2)