5 Signal Description

The following tables provide the details on signal names classified by the peripheral.

Table 5-1. Signal Descriptions List
Signal Name	Function	Type
Analog Comparators (AC)
AIN[3:0]	AC Analog Inputs	Analog Input
CMP[1:0]	AC Comparator Outputs	Digital Output
Analog-to-Digital Converter (ADCx)
AIN[11:0]	ADC Analog Inputs	Analog Input
VREFA⁽¹⁾	ADC Voltage External Reference A	Analog Input
External Interrupt Controller (EIC)
EXTINT[15:0]	External Interrupts inputs	Digital Input
NMI	External Non-Maskable Interrupt input	Digital Input
General Purpose I/O (PORT)
PA31-PA30, PA28-PA27, PA25-PA00	General Purpose I/O Pin in Port A	Digital I/O
PB23-PB22,PB11-PB08,PB03-PB02	General Purpose I/O Pin in Port B	Digital I/O
Generic Clock Generator (GCLK)
GCLK_IO[7:0] ⁽²⁾	Generic Clock Source (Input) or Generic Clock Signal (Output)	Digital I/O
Custom Control Logic (CCL)
IN[11:0]	Inputs to lookup table	Digital Input
OUT[3:0]	Outputs from lookup table	Digital Output
Power Manager (PM)
RESET_N	External Reset Pin (Active Level: LOW)	Digital Input
Serial Communication Interface (SERCOMx)
PAD[3:0]	SERCOM Inputs/Outputs Pads	Digital I/O
Oscillators Control (OSCCTRL)
XIN	Crystal Input or External Clock Input	Analog Input (Crystal Oscillator) Digital Input (External Clock)
XOUT	Crystal Output	Analog Output
32 kHz Oscillators Control (OSC32KCTRL)
XIN32	32 kHz Crystal Input or External Clock Input	Analog Input (Crystal Oscillator) Digital Input (External Clock)
XOUT32	32 kHz Crystal Output	Analog Output
Timer Counter (TCx)
WO[1:0]	Waveform Outputs	Digital I/O
Timer Counter (TCCx)
WO[7:0]	Waveform Outputs	Digital I/O
Serial Wire Debug Interface
SWCLK	Serial Wire Debug Clock	Digital Input
SWDIO	Serial Wire Debug Data	Digital I/O

Note:

VREFA is shared between the ADC peripherals.
GCLK8 does not support an input/output on a pin.