CHAPTER 2 PIN FUNCTIONS
User’s Manual U15331EJ4V1UD 43
2.2.13 RESET
This pin inputs an active-low system reset signal.
2.2.14 X1, X2
These pins are used to connect a crystal resonator for main system clock oscillation.
To supply an external clock, input the clock to X1 and input the inverted signal to X2.
2.2.15 XT1, XT2
These pins are used to connect a crystal resonator for subsystem clock oscillation.
To supply an external clock, input the clock to XT1 and input the inverted signal to XT2.
2.2.16 AVDD
This is the analog power supply pin of the A/D converter. Always use the same potential as that of the VDD pin even
when the A/D converter is not used.
2.2.17 AVSS
This is the ground potential pin of the A/D converter. Always use the same potential as that of the VSS pin even
when the A/D converter is not used.
2.2.18 VDD
This is the positive power supply pin.
2.2.19 VSS
This is the ground pin.
2.2.20 VPP (flash memory version only)
A high voltage should be applied to this pin when the flash memory programming mode is set and when the
program is written or verified.
Handle the pins in either of the following ways.
• Independently connect a 10 kΩ pull-down resistor.
• Switch this pin to be directly connected to the dedicated flash programmer in programming mode or to VSS in
normal operation mode using a jumper on the board.
If the wiring between the VPP pin and VSS pin is very long or external noise is superimposed on the VPP pin, the
user program may not run correctly.