How to find the digital and analog pins on a standard Arduino board

The tables below show the digital and analog pins for a standard Arduino board and the Mega board.

The “Port” column lists the physical port used for the pin.

Analog and digital pin assignments common to popular Arduino boards

	Arduino 168/328			Arduino Mega (Pins 0-19)
Digital pin	Port	Analog Pin	Usage	Port	Analog pin	Usage
0	PD 0		USART RX	PE 0		USART0 RX, Pin Int 8
1	PD 1		USART TX	PE 1		USART0 TX
2	PD 2		Ext Int 0	PE 4		PWM T3B, INT4
3	PD 3		PWM T2B, Ext Int 1	PE 5		PWM T3C, INT5
4	PD 4			PG 5		PWM T0B
5	PD 5		PWM T0B	PE 3		PWM T3A
6	PD 6		PWM T0A	PH 3		PWM T4A
7	PD 7			PH 4		PWM T4B
8	PB 0		Input Capture	PH 5		PWM T4C
9	PB 1		PWM T1A	PH 6		PWM T2B
10	PB 2		PWM T1B, SS	PB 4		PWM T2A, Pin Int 4
11	PB 3		PWM T2A, MOSI	PB 5		PWM, T1A, Pin Int 5
12	PB 4		SPI MISO	PB 6		PWM T1B, Pin Int 6
13	PB 5		SPI SCK	PB 7		PWM T0A, Pin Int 7
14	PC 0	0		PJ 1		USART3 TX, Pin Int 10
15	PC 1	1		PJ 0		USART3 RX, Pin Int 9
16	PC 2	2		PH 1		USART2 TX
17	PC 3	3		PH 0		USART2 RX
18	PC 4	4	I2C SDA	PD 3		USART1 TX, Ext Int 3
19	PC 5	5	I2C SCL	PD 2		USART1 RX, Ext Int 2

Assignments for additional Mega pins

Arduino Mega (pins 20–44)			Arduino Mega (pins 45–69)
Digital pin	Port	Usage	Digital pin	Port	Analog pin	Usage
20	PD 1	I2C SDA, Ext Int 1	45	PL 4		PWM 5B
21	PD 0	I2C SCL, Ext Int 0	46	PL 3		PWM 5A
22	PA 0	Ext Memory addr bit 0	47	PL 2		T5 external counter
23	PA 1	Ext Memory bit 1	48	PL 1		ICP T5
24	PA 2	Ext Memory bit 2	49	PL 0		ICP T4
25	PA 3	Ext Memory bit 3	50	PB 3		SPI MISO
26	PA 4	Ext Memory bit 4	51	PB 2		SPI MOSI
27	PA 5	Ext Memory bit 5	52	PB 1		SPI SCK
28	PA 6	Ext Memory bit 6	53	PB 0		SPI SS
29	PA 7	Ext Memory bit 7	54	PF 0	0
30	PC 7	Ext Memory bit 15	55	PF 1	1
31	PC 6	Ext Memory bit 14	56	PF 2	2
32	PC 5	Ext Memory bit 13	57	PF 3	3
33	PC 4	Ext Memory bit 12	58	PF 4	4
34	PC 3	Ext Memory bit 11	59	PF 5	5
35	PC 2	Ext Memory bit 10	60	PF 6	6
36	PC 1	Ext Memory bit 9	61	PF 7	7
37	PC 0	Ext Memory bit 8	62	PK 0	8	Pin Int 16
38	PD 7		63	PK 1	9	Pin int 17
39	PG 2	ALE Ext Mem	64	PK 2	10	Pin Int 18
40	PG 1	RD Ext Mem	65	PK 3	11	Pin Int 19
41	PG 0	Wr Ext Mem	66	PK 4	12	Pin Int 20
42	PL 7		67	PK 5	13	Pin Int 21
43	PL 6		68	PK 6	14	Pin Int 22
44	PL 5	PWM 5C	69	PK 7	15	Pin Int 23

The table below is a summary of timer modes showing the pins used with popular Arduino chips.

Timer modes

Timer	Arduino 168/328	Mega
Timer 0 mode (8-bit)	Fast PWM	Fast PWM
Timer0A `analogWrite` pin	Pin 6	Pin 13
Timer0B `analogWrite` pin	Pin 5	Pin 4
Timer 1 (16-bit)	Phase correct PWM	Phase correct PWM
Timer1A `analogWrite` pin	Pin 9	Pin 11
Timer1B `analogWrite` pin	Pin 10	Pin 12
Timer 2 (8-bit)	Phase correct PWM	Phase correct PWM
Timer2A `analogWrite` pin	Pin 11	Pin 10
Timer2B `analogWrite` pin	Pin 3	Pin 9
Timer 3 (16-bit)	N/A	Phase correct PWM
Timer3A `analogWrite` pin		Pin 5
Timer3B `analogWrite` pin		Pin 2
Timer3C `analogWrite` pin		Pin 3
Timer 4 (16-bit)	N/A	Phase correct PWM
Timer4A `analogWrite` pin		Pin 6
Timer4A `analogWrite` pin		Pin 7
Timer4A `analogWrite` pin		Pin 8
Timer 5 (16-bit)	N/A
Timer5A `analogWrite` pin		Pin 46
Timer5A `analogWrite` pin		Pin 45
Timer5A `analogWrite` pin		Pin 5

Note that the Arduino column is for the ATmega 168/323, and the Mega column is for the ATmega 1280/2560.

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