3.1 I/O Multiplexing


VQFN20	SOIC20	SOIC14	Pin name ^(1,2)	Special	ADC0	AC0	DAC0	ZCD3	USARTn	SPI0	TWI0⁽⁴⁾	TCA0	TCBn	TCD0	EVSYS	CCL-LUTn
17	4	4	PA0	XTAL32K1 XTALHF1 EXTCLK					0,TxD		SDA(H)⁽³⁾	WO0				0,IN0
18	5	5	PA1	XTAL32K2 XTALHF2					0,RxD		SCL(H)⁽³⁾	WO1				0,IN1
19	6		PA2	TWI Fm+	AIN22				0,XCK 0,TxD⁽³⁾		SDA(H)	WO2	0,WO		EVOUTA	0,IN2
20	7		PA3	TWI Fm+	AIN23				0,XDIR 0,RxD⁽³⁾		SCL(H)	WO3	1,WO			0,OUT
1	8		PA4		AIN24				0,TxD⁽³⁾	MOSI		WO4		WOA
2	9		PA5		AIN25				0,RxD⁽³⁾	MISO		WO5		WOB
3	10		PA6		AIN26				0,XCK⁽³⁾	SCK				WOC		0,OUT⁽³⁾
4	11		PA7	CLKOUT	AIN27	OUT		ZCOUT	0,XDIR⁽³⁾	SS				WOD	EVOUTA⁽³⁾
5	12	6	PC1		AIN29⁽⁶⁾				1,RxD 0,TxD⁽³⁾	MISO⁽³⁾ MOSI⁽³⁾		WO1⁽³⁾				1,IN1
6	13	7	PC2	TWI Fm+	AIN30⁽⁶⁾	AINN3⁽⁶⁾		ZCIN	1,XCK 0,RxD⁽³⁾	SCK⁽³⁾ MISO⁽³⁾	SDA(C) SDA(H)⁽³⁾	WO2⁽³⁾			EVOUTC	1,IN2
7	14	8	PC3	TWI Fm+	AIN31⁽⁶⁾	AINP4⁽⁶⁾			1,XDIR 0,XCK⁽³⁾	SS⁽³⁾ SCK⁽³⁾	SCL(C) SCL(H)⁽³⁾	WO3⁽³⁾				1,OUT
8	15	9	VDDIO2
9	16	10	PD4		AIN4				0,TxD⁽³⁾	MOSI⁽³⁾		WO4⁽³⁾		WOC⁽³⁾
10	17	11	PD5		AIN5				0,RxD⁽³⁾	MISO⁽³⁾		WO5⁽³⁾		WOD⁽³⁾
11	18	12	PD6		AIN6	AINP3	VOUT		0,XCK⁽³⁾ 1,TxD⁽³⁾	SCK⁽³⁾						2,OUT⁽³⁾
12	19	13	PD7	VREFA	AIN7	AINN2			0,XDIR⁽³⁾ 1,RxD⁽³⁾	SS⁽³⁾					EVOUTD⁽³⁾
13	20	14	VDD
14	1	1	GND
15	2	2	PF6⁽⁵⁾	RESET
16	3	3	PF7	UPDI						SS⁽³⁾					EVOUTF⁽³⁾

Note:

The pin names are Pxn type, with x being the PORT instance (A, B, C, ...) and n, the pin number. The notation for signals is PORTx_PINn. All pins can be used as event input.
All pins can be used for external interrupt.
Alternate pin positions. Refer to the PORTMUX - Port Multiplexer section for selecting the alternate positions.
The TWI pins that can be used as host or client are marked H. The pins with client-only are marked C.
Input-only.
ADC and AC inputs are available on MVIO pins (PORTC) if the MVIO is disabled in the SYSCFG1.MVSYSCFG fuse setting.