Renesas RA Family
RA2 Quick Design Guide
R01AN6060EU0100 Rev.1.00
Page 30 of 44
Sep.14.21
Figure 22. Configure IRQ03 using Renesas FSP Configurator
9.5 Unused Pins
Note:
Some pins require specific termination: See the “Handling of Unused Pins” section of the Hardware
User’s Manual for specific recommendations.
Unused pins that are left floating can consume extra power and leave the system more susceptible to noise
problems. Terminate unused pins with one of the methods detailed here:
1. The first option is to set the pin to an input (the default state after reset) and connect the pin to VCC or
VSS using a resistor. There is no difference to the MCU between one connection or another; however,
there may be an advantage from a system noise perspective. VSS is probably the most typical choice.
Avoid connecting a pin directly to VCC or VSS since an accidental write to the port’s direction register that
sets the pin to an output could create a shorted output.
2. A second method is to set the pin to an output. The pin level may be set high or low. However, setting the
pin as an output and making the output low connects the pin internally to the ground plane. This may help
with overall system noise concerns. A disadvantage of setting unused pins to outputs is that the
configuration of the port must be done via software control. While the MCU is held in reset and until the
direction register is set for output, the pin will be a floating input and may draw extra current. If the extra
current can be tolerated during this time, this method eliminates the external resistors required in the first
method.
3. A variation on leaving the pins as inputs and terminating them with external resistors uses the internal
pull-ups available on many ports of the MCU. This has the same limitation as setting the pins to outputs
